Protected cells end up being a little longer and very slightly wider in diameter because a protection circuit is added on the end and then the cell is wrapped to keep it in place. So for example, the 2900mAh AW and Redilast 18650s are both Panasonic NCR18650 batteries with an added protection circuit. Here is a picture of one that has been disassembled.
An unprotected NCR18650 is approximately 65 mm in length, and the re-branded, protected versions are around 68 - 69 mm.