Parallel jobs are carriedout on miltiple nodes/processors 
but in server jobs no multitasking is there to talk in 
simple terms. There are many technical differences like no 
server sort stage etc but this is the basic difference

Parallel jobs are carriedout on miltiple nodes/processors 
but in server jobs no multitasking is there to talk in 
simple terms.

In parallel we can have multiprocessing (multinodes), But 
in server its not there.

Server working with pipeline concept,parallel working in 
the principle of parallelism

Parallel job run on multithreading where as server job run
on singlethread.
parallel job we can use millions of data to run by using
nodes and partition where server job we can use small amount
of data so that the output will be retrived faster,since it
single threading.

SERVER JOBS                   PARALLEL JOB


RUN ON        SINGLE NODE                   MULTIPLE NODE
 

PIPELINING & 
PARTITIONING   DOES NOT SUPPORT             SUPPORTS 

LOADS          WHEN 1 JOB FINISH             SYNCHRONIZED  
 
SERVER JOBS USES            
SYMMETRICMULTIPROCESSING                         
 
PARALLEL JOBS
BOTH  MASSIVE  PARALLEL PROCESSING AND  
SYMMETRICMULTIPROCESSING