Although they are all abbreviations, they have different meanings. I don't know what you mean. Here are some examples:

BLF is the abbreviation of the following words

The abbreviation of Busy Lamp Field is a service name in IP communication.

Band-limited filter

Bright line viewfinder visual viewfinder

Bubble lattice file memory

BLA is the abbreviation of the following words

Bachelor of Arts (Bachelor of Arts)

Beam landing zone of Bearn landing zone

Application for biological products license

Biological License Agreement (FDA) Biotechnology License Agreement (FDA)

Bank loan agreement