The suffix “UF” compared to “TF” is explained in the datasheet for the part VSSR16-220-JI-ND; VSSR1603221JUF. UF means tube packaging while TF means a full reel containing 2500 pieces. This info is on page 3.
https://www.vishay.com/docs/60003/vtsrvssr.pdf is the link for the datasheet.