Refinancing that omits some of the standard risk control measures and is therefore quicker and less costly.
The rationale for streamlined refinancing is that, while it is an entirely new loan, the information from the previous loan available to the lender retains validity. In addition, valuable information may be available on the borrower's payment history.
The extent to which a lender can offer streamlining depends on how much information and how much discretion the lender has. A new lender that was the original lender and still owns the loan has the greatest leeway. A new lender that was the original lender but is now servicing the loan for someone else has the same information but less discretion. Anew lender that was not the original lender and is not servicing the old loan doesn't have the information needed to justify streamlined refinancing.
See Refinance/Refinancing with the Current Lender.