These are two separate things, as we know that neechabhanga can occur in multiple forms (for eg. planet's neechnath is in kendra from moon OR strong neechnath aspects its own house etc.), if a given planet's neechabhanga occurs in multiple ways, then we say that, this planet will behave as if it's not neecha and it's a rajyoga for the native, this situation is called neechabhanga rajyoga.

For eg. In Cancer lagna, if Mercury is placed in the 9th house in meen rashi, it'll become neecha, suppose moon is in 7th house and Jupiter is in 1st house, now, we can say that since strong Ju aspects its own house (meen rashi), one type of neechabhanga has occurred, since lord of the neecharashi (neechnath) is in kendra from moon, another type of neechbhanga has happened, lord of neechrashi Ju is itself exalted, causing third type of neechbhanga, this is a neecbhanga rajyoga, now we can practically assume that Mercury will give no/very less results of being debilitated.

Hope this was helpful :)