what is the difference FileList and flow to iterate, tmap : Var block and adding new column in tmap outpu

[havaldarsmitha]

What is the difference between FileList and Flow to iterate? that can be used interchangeably? 

In tmap what is the use of "var". If we can create new column directly in tmap output then why do we need "Var"?

[manodwhb]

Filelist component will list the files which are there in folder for the specified filemask.

Flow to iterate is that component to iterate record by record to next logic which is defined after flowtoiterate.

In tmap, var sections are important to compare current value with previous value of column based one requirement.