It is two completely different games.You are mistaken. He started with the NTR route, once that was finished and released, he switched to the Love route. He'll probably do NTR route again and then once again switch back to Love route. Many devs follow this approach where they do a release per route, or take twice as long and release both routes together.
The first one, it was her sister living with them. In the second one she was the MC's best friend.
The first one they had a foursome and the MC could choose to take the sister's virginity or allow the other man to do it
The first one the MC's girlfriend had a "free pass" during the fun, but then she left in the middle of the night and chose to cheat and have unprotected sex and be creampied. She and the new lover even hinted at continuing in secret. She came back to bed with the MC and speaking to her sleeping boyfriend said something about the fact that if he only new what they started. Then it ended.
Now the second one has nothing todo with the first. It is completely different. I was hoping to explore the first...
But oh well...