Habibti is a female word and it means “My beloved”. “Habibi” is male and it’s means “My dear one.”
For Arabic speakers, the difference between these two words is represented by the gender. For English speakers, one word may seem more intimate than another but this perception may not line up with the intended meaning. In both cases, they denote an extreme amount of love and affection for that person. So in some sense, they are really interchangeable if you’re using them for someone whose gender aligns perfectly with what we’ve taught you about their language of choice so far.