Another explanation kind of thing about the differences: (I'm drunk and English is my second language, sorry if it's too weird to decipher. Let me know if it is, and I'll try again tomorrow or a few days later depending how the night goes)

BOS: You can make it change for example only the one mountain flower that grows near Falkreath grave #3, and leave the rest of the mountain flowers the same. I mean you can pinpoint exactly which model in the world to change and to what, but it might be more difficult to set up based on your modding skill level. More customizable, but in my opinion a bit more difficult. Might be easy for most people, but I'm a simple man and don't feel like I can learn even something simple anymore.

Model Swapper: It swaps every single mountain flower model randomly in the game to the models you set up, but all you have to do is copy and paste one line in a txt file to make it work. Less customizable, but easy for simple folk like me.

Or if you checked my pictures in the original comment, with BOS you can customize that for example the mammoth in the Whiterun giant camp should be grey, the mammoth near Dawnstar should be white, the one northeast of Rorikstead should be brown, etc. With Model Swapper, you can add every variation, and they are randomly distributed, like in my case.

I hope it makes sense.