sp_who2 returns

SPID --> which is the process under consideration

BLK --> if it has a value represents the SPID of the blocking process

Ex. SPID =10 BLK=51 --> Process 10 is being blocked by process 51

sp_lock return all process request or in lock states unless the status is grant state.

-- Returns information about currently active lock manager resources.

select * from sys.dm_tran_locks