Question about extracting data from different. options availabe in OLEDB Source

This may seem very simple for many of seasoned SSIS punters. I wanted now for extracting data from OLEDB source we use different options like
- Table Or View
- Table Name Or View Name from variable
- SQL Command
- SQL Command from variable

My question is all there options does the same thing. Why these many number of options. Please let me know.

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Smash126