Business sytem require all details like login user id 
password require to create but in case of business service 
log in details does not require..


regards.

KRUSHI

A Business System  is purely for SAP-Systems and
Business Service for Non-SAP systems

let me know if i am wrong .........

Business service refers to any business applications where
as the business system is defined in SLD(System Landscape
Directory)

When we have full details of application system the we are 
going to use the business system and it is created in the 
SLD so we dont have authorization to change the business 
system name.

When we have partial details or no details of Technical 
system then we r going to use the business service. it is 
created in the ID. we can see and change it.

A Business system is something that physically exists

For example, if u want to download a file from a system 
ABC, by using file adapter and then want to update the 
content of this file into r/3 database by using RFc,then 
the system  abc and the r/3 will be ur business systems
i.e. they physically exists. Business Systems are 
configured in SLD.
Business service is mostly usedin B2B Scenario (cross-
component),where you don't know the Business System of your 
partner. In other words business Service will be used only 
for those partners which do not have a physical landscape 
set up . Business servces do not have an entry in SLD.

A Business Service is an Abstract Unit(which is not in 
System Landscape Directory) addressing Senders and 
Receivers of Messages.

Physicals systems which use their communication channels 
and routing rules to communicate with other systems are 
called as Application Systems OR physical systems.

In simple when u going for A2A integration then we define 
our Technical systems are Business system. If we r going 
for B2B integration then we dont know the complete 
information about the other end Business Landscape so, we 
configure it as a Business Services. Business system are 
created at SLD. Where as a Business Services are created at 
Integration Directory.

Still u have any query u can send at cravisap@gmail.com