In reply to SHRI12326:
The source code for the class
uvm_tlm_analysis_fifo shows you precisely what the differences are.
The class
uvm_tlm_fifo supports both bounded and unbounded fifos. But when the constructor of
uvm_tlm_analysis_fifo calls super.new(), it fixes the size argument to unbounded, 0. It also constructs an analysis_export, which implements the necessary write() method, which calls the fifos try_put() method.