The RAF just does not seem to bother with designating operational trial squadrons as such.
Yep, the RAF didn't have test units of the same nature as Ekdo 262; new types were introduced into squadron service, where their issues were worked through at squadron level, often by a Flight. Since the war, pilots went through the Operational Conversion Unit in terms of training on a new type and generally that was introduced through the OCU, rather than straight to squadron service, although this applied to combat aircraft only. A number of the OCUs were formed by Flights of personnel evaluating a new type.
If we are still nitpicking over the difference between Ekdo 262 and 616 Sqn, the primary difference between the two is that 616 (South Yorkshire) Squadron was was an Auxiliary Air Force unit formed in 1938 and relinquished its Spitfire HF.VIIs for Meteor Is in 1944, so it was already a combat unit within the RAF structure and not formed specifically to trial the Meteor.