DE stands for Direct Endorsement.  It is reference to the ability to underwrite FHA loans.  If a company has DE underwriters, it means that it has the ability to endorse the application package and approve the loan.  A company without a DE underwriter must correspond with a lender that does have one if it wants to do FHA loans.  Not having DE ability adds to the length of time to process, underwrite and approve a loan file.  It can sometimes means less favorable loan pricing as well.  HUD, the department of the Federal Government that oversees FHA, used to underwrite files, but they delegated that function to lenders who had DE underwriters some time ago. 

In short, a company with a DE underwriter has an edge on one who doesn't have one.