Transactional immunity is commonly known as total immunity. When someone gets transactional immunity, they cannot be prosecuted for the crime in question or a related crime.
There are three major differences between transactional and use immunity: independent evidence of the crime; additional crimes; and perjury.
If someone is granted use immunity in a robbery case, their testimony cannot be used to prove they are guilty of the robbery. If, on the other hand, the police find the person’s fingerprints at the crime scene and the stollen goods in their house, the additional evidence can be used to prove the robbery.
If someone is granted immunity to testify about a drug crime and admits to a robbery, their testimony can be used to prove guilt in a robbery case. The prosecutor doesn’t need any independent evidence to establish guilt of the robbery.
Obviously, a person granted use immunity is not protected if they commit perjury during their testimony.
This page from the Department of Justice discusses use immunity.