Well, one big difference is that they have detailed teachings on the process of rebirth and the Bardo, the state between death and rebirth. The older Therevadhan school has no Bardo state, they believe that you take rebirth instantly when they die. And other Mahayana schools just don't say much about the process.
Also in Tibetan Buddhism they have a process of identifying rebirths of some meditators who they believe have an ability to direct their rebirth and leave instructions for how to find their next rebirth. Just a tiny percentage of the population do that, but still, thousands of rebirths identified that way.
That's a bit unusual, especially since the Buddha warned us against trying to identify our previous rebirth as that can lead to pre-occupation with trying to find a common self and strengthening the illusion of a self.
There is nothing inconsistent between the teachings on non self and rebirth, or identifying rebirth. After all a young baby can grow up to be an adult and then an old person, so why not an old person take rebirth as a baby? And the Buddha taught for nearly 45 years after he realized non self in his mid thirties as traditionally believed. So the teachings on non self, whatever they mean, are consistent with being the same person now as you were as a child, and with taking rebirth, and indeed identifying rebirth.
But the Buddha warned us against trying to find out who we were in our previous life due to pre-occupations with trying to find a common self between this and previous lives that could arise.
So the Tibetans are a bit unusual in their approach of identifying rebirths of particular lamas. I wouldn't say they are going against the Buddha's teachings in this. They've managed to make it work in their society and it doesn't seem to cause any problems. But just that most Buddhist traditions don't do this.
I suppose it is a little different if you actually know who you were in a previous life, rather than to get distracted trying to find out when you don't know which is what the Buddha warned us about. After all it is not a big deal that I know who I was when I was a baby, and I don't spend my life distracted and worked up about that, trying to find out which baby I was in the historical records, as I already know - so I suppose it is the same as that.
As well as that the Tibetans have many esoteric teachings, in the Vajrayana for instance teachings on inner heat that keep you warm in sub zero conditions. And elaborate colourful meditations and "visualizations" that some meditators do, which you don't have in most Buddhist traditions.
They have an especially rich tradition of long meditative retreats. Again not unique to Tibetan Buddhism, you get long retreats like that in other branches also. However I think perhaps a bit unusual, the number of Tibetan meditators who spend many years, often decades, and sometimes their entire liftetime in retreat. Which they don't think of as escaping from the world or retreating from it, but rather, as even more involved and interconnected with the world because they are on retreat. And others feel that there are great blessings involved in supporting them and that by doing this they help everyone.
Many of the elaborate meditations relate to problems that meditators have in these long retreats. They are sort of "problem solving" meditations and - ordinary beginner meditators don't need them and most Tibetans also wouldn't do them. Often Tibetan teachers teach these colourful meditations to beginners in the West - but when they do that I think it is surely, in most cases, by way of a blessing connection except in the case of the few dedicated meditators who go on to study for years and then do long multi-year retreats like the most dedicated Tibetan meditators.
And most Tibetans of course, as in any culture, are not retreatants or meditators, but just ordinary people doing ordinary jobs or relaxing and leading ordinary lives - but inspired by their Buddhist beliefs and with Buddhist ideas integrated deep into their language.
And they also make extensive use of mantras, sequences of syllables that you can repeat to yourself, to make a connection with aspects of enlightenment. For instance Om Mani Padme Hung, the famous mantra that Tibetan Buddhists believe carries the blessings of enlightened compassion. They carve this mantra on rocks, and they put it on prayer flags and inside wheels which they spin around. So, I think they use mantras rather more than other traditions.
Perhaps in some ways most visible difference is this omnipresence of this mantra in Tibetan script. And all the colourful visualizations in the Tankhas and statues which they believe also carry the blessings of various aspects of enlightenment. They aren't deities, not external deities as such. They represent qualities of enlightenment that we all have in ourselves that we could open out to and which can lead to spontaneous acts of altruism, compassion, loving kindness, generosity etc. in anyone. If you do somethig particularly compassionate a Tibetan might say that you are Chenrezig at that moment - the enlightened aspect of compassion.
Tibetans also firmly believe in demons and "deities" long lived celestial beings. These are not an integral part of Buddhism, but many Buddhist cultures have them, as do other Indian derived religions, so they are not particularly specific to Tibetan Buddhism.
And the idea of a bodhisattva is common to all branches of Buddhism including Therevadhan Buddhism. So you can have Therevadhan bodhisattvas. And those who try to follow the bodhisattva path in Tibetan Buddhism may be doing it mainly with the wish to help themselves in which case it is more of a first inspirational or blessing connection with the bodhisattva path. So that's not really a major difference.
And just a cultural difference, that they use specifically Tibetan symbols, and images in their art, and the Tibetan script. As Buddhism spreads in the West it will surely develop new distinctive Western cultural practices and representations of Buddhist aspects of enlightenment.
There are subtle differences of ideas and philosophies about such things as emptiness and karma, between all the schools of Buddhism, and in Tibet the four schools there have differing ideas also. A scholar of Tibetan Buddhism might talk mainly about these. But this is a very subtle and difficult area of study, and I'm not knowledgeable in this area. It is not so much that there is something subtle and difficult about enlightenment itself. It's rather that if you start talking about it and approaching it via constructing philosophies, then you easily get caught up in many intricate debates. Basically we make it complicated because we are complicated. But in the stories many meditators bypass all that and go straight to enlightenment sometimes based on simple practices, a few words of explanation and much dedication. So you don't first have to be an academic philosopher to become enlightened. Yet for some practitioners this debating of intricate ideas is what they need, part of the path, and helps them. So it is a useful part of the teachings for some practitioners.
And I think from what I do know that there is probably as much difference between the four main Tibetan schools on these points as there are between some of the Tibetan schools and some non Tibetan schools of Buddhism on these points. For instance the differences in ideas about "Buddha nature" - some Tibetan schools talk about this and some don't and some non Tibetan schools talk about this and some don't.