Lately I've been reading the einreise law due to corona situation. I've noticed a use of these two words (lebensgefährte und lebenspartner), but after googling a bit couldn't find a differnce between them - both are translated as life partner (both to English and my native language Russian). I guess they are very similar, with a slight emotional or legal difference.
Specifically it's being used in the Hessen corona einreise VO regulations:
"Personen, die einreisen aufgrund des Besuchs von ... Lebensgefährtinnen, Lebensgefährten, Lebenspartnerinnen, Lebenspartnern oder ..."