Please remember Nepal Bhasha is spoken by Newars
Nepali (the national language of Nepal), or khas bhasha is spoken in a lot of places in India, Nepal, Burma, Bhutan etc.

The name Nepal and,Nepali was originally used by people in Kathmandu valley before king prithvi narayan Shah won Kathmandu.

Before that although the Nepali language was spoken in a broader region ranging from east of Asham (now a state of India), similarly in the west to nainital.

Newars lost the war, but still refer themselves as Nepali and refer their own  calendar as Nepal sambat, language as Nepal Bhasha. People still refer Kathmandu as Nepal.

GIST: Nepal Bhasha  is spoken by Newars.  new.wikipedia.org
Nepali is: ne.wikipedia.org.

Please correct if I missed something,