Both animal and vegetal FAT are completely different. They are tagged FAT for simplification. They are called FAT even when they are composed of thousands of different components (and in different quantities). For example, Omega-3, that you could eat (as vegetal) naturally but in limited quantities.

However, the main problem is not the FAT but proteins, they are also really different but molecules of proteins are more complex than fat. Even if your diet is rich vegetal-protein, you will need supplements, a lot of it.

If you are vegan, then you know the drill. If you don’t then you could see the consequences in a couple of decades.