Difference in count of messages in Intgrn engine and adptr engine

Hi,

In RWB. the number of messages displayed in Integration Engine (database Overview) and Adapter Engine (database Overview) are different.

THe no of messages in IE is 38709 wer as no.of messages in adapter engine is 38692..

Does it mean the rest of the files are not delivered to FTP?

I dont see anyh error messages or queues in PI. So why is difference ?

Any help would be appreciated