As nouns the difference between fids and fits

is that fids is plural of lang=en while fits is plural of lang=en.

As an initialism FIDS

is Flight Information Display System; a key system of every airport for displaying actual flight information on several display devices (e.g. monitors, LED boards, etc.) and Intranet real-time information distribution/broadcasting for airport staff.

As a verb fits is

third-person singular of fit.