What is the difference between Trim() and Trim$()?

VBA string functions Left, Right, Mid, LTrim, RTrim, Trim (used to get a portion of a string/variant) can used for string and variant. Adding $ at the end means they can be used for string only, cannot accept null value. 

For example"
Trim(Null) will return Null, while Trim$(Null) will raise a run-time error
94 ("Invalid use of Null").