Is there a difference between paneer butter masala, matar paneer, malai kofta gravy? It seems to me that although you can find different recipes for each of the dishes described above, the gravy is basically the same, with the only difference for example between paneer butter masala and matar paneer is that matar paneer has peas in it.

(The gravy I'm taking about - frying cumin seeds, onions, ginger garlic paste, tomato, adding ground cumin, ground coriander, chilly powder, blending with cahshew paste and then adding cream and kasuri methi)

Am I correct in assuming this?

In addition - It seems to me that the same thing could be said about aloo gobi, channa masala, baingan bharta, and many other dishes - Basically the same frying of onions, ginger garlic paste and tomatoes, but with a different ingredient added at the end (for example eggplant for baingtan bharta).

If the recipes are actually the same, then it would mean a lot of the Indian dishes have a similar taste... I'm interested in the dishes as they are cooked in authentic Indian restaurants.
Paneer butter masala, malai kofta gravy and matar paneer are part of the North Indian cuisine where the base is mostly the same with some minor variations (like excluding cumin seeds). 

So essentially, you have a common base gravy for sweeter dishes like these and then you have a spicier gravy for other dishes.
Many Indian cuisines have this pattern. For example, Gujarati cuisine will have red chili powder, turmeric, garlic-ginger, mustard seeds, cumin powder, fenugreek, cilantro and jaggery, etc. as a general base with some additions and subtractions of the vegetable ingredients. 
Similarly, you'll be able to find common base gravies across Indian recipes and cuisines. 

But, when you say:
"In addition - It seems to me that the same thing could be said about aloo gobi, chana masala, baingan bharta, and many other dishes - Basically the same frying of onions, ginger garlic paste and tomatoes, but with a different ingredient added at the end (for example eggplant for baingan bharta)."

You are making a generalization which is not necessarily true. These recipes can vary quite a bit based on regional tastes, specially baingan ka bharta. This dish is a signature dish and needs a seasoned hand to deliver it right.

So, you are right when you say there is a common pattern across recipes.
But certain dishes like aloo gobi will exist in different forms across the country. But rest assured malai kofta, paneer butter masala and matar paneer are only prepared in the North Indian style.