Hi Pushkar,
BOM is required in order to plan and produce a production lot and to determine its costs. We can use an existing material BOM, create a work breakdown structure BOM for each individual production lot or you can use one work breakdown structure BOM for several production lots of a material.
WBS BOM's are created specific to WBS element of Project. Material BOM's are for Production Planning.
CS71 - Create WBS BOM
CS72 - Change WBS BOM
CS73 - Display WBS BOM
CS20 - Mass changes
CSPB - WBS BOM browser
CS01/CS02/CS03 - Create/ change/display material BOM.
Refer to the below thread for more clarification.
Thanks & Regards,
Ramagiri