I'm always a little hesitant to post here, I'm not a real historian so I feel a bit out of place, but I'd like to weigh in here and if an actual historian would like to clean up my interpretation I wouldnt mind at all.

The main advantage in my assessment of the tactic is that a glider full of troops all disembark the aircraft at the same point, which speeds the pace of the critical early minutes of the assault. Team integrity lends itself to highly delineated task organization, maximizing effectiveness with small numbers of well rehearsed troops. Paratroopers, on the other hand, were often disaggregated by high winds, fast moving aircraft, and the lack of any steering controls on early parachutes. This disaggregated force then has to reconsolidate on the ground in order to regain combat effectiveness as a team.

While British and US forces both employed gliders as assault insertion aircraft in WWII, it's my opinion that the true masters of the glider were the Germans, with the best example of this prowess being the raid on Fort Eben-Emael. There's a fine summary of the battle in the book "Spec Ops: Case Studies in Special Operations Warfare: Theory and Practice" by Admiral William McRaven, the current commander of USSOCOM. At Eben-Emael, gliderborne commandos were able to achieve poinpoint landings near their individual objectives, and then prosecute those objectives quickly and decisively.

I don't understand the premise of the question. The British also used paratroops, and the US also used gliders.

A glider had several advantages vs parachutes.

A glider could carry an entire squad into the same area without fear they would be dispersed via the wind like many parachute units were on D-Day while at the same time allowing them more kit and much less bulk since the glider can carry equipment rather than the soldiers carrying all of it.

The glider also can carry a jeep in it which makes it a great choice for an officer that needs to quickly link up with his units to make sure they are all ok etc.

A glider can be "steered" which offers a much higher chance of actually hitting the designated DZ rather than relying on the whim of nature to get them there.

Also gliders are much less obvious than parachutes. A plane would "launch" a glider where it would then glide to its objective. In doing so the enemy doesn't know exactly where the glider is, its exact objective rather assuming it was likely a bomber passing overhead. In comparison a parachute chalk would have many aircraft and many parachutes covering the sky making it extremely obvious to anyone who looked up.

The gliders had cons however since it took much more effort to use one and more specialized training. It was also expensive since you were in essence using a "throw-away" vehicle that was used once and never again (unless it could be recovered). Also it was good for dropping in individual units but for a large invasion where everyone knew you were coming anyway, it was much more cost efficient to use parachutes and drop en-mass.

This part here im not sure about. The British used parachutes and did drop them along side US troops (however they had 1 less reserve chute) and they also did use gliders. I think the gliders were used for commando units that needed to be stealthy and land reliably on target while parachuters did not. So rather, the gliders were for a different role entirely than the parachute was, insertion rather than invasion.

Hope that helped.

The US did use gliders also, during WW2. The 325th Glider Infantry regiment (of the 82d AB) and the 327th GIR of the 101st are two units that are still around, albeit not in the same form.

I think that in some of the British Airborne missions troops were needed to capture a specific structure such as a bridge e.g. Pegasus Bridge or Arnhem. Gliders would be better for this as they transport a group of troops all to the same place and allow structures to be captured quickly. With the US the airborne troops were often used to occupy important towns or areas e.g. St Lo so more troops were needed but they didn't have to land in the same small area, they could attack from different points. I'm not a historian so don't take my word for it but I think it may just be due to the mission they were undertaking not the army's preference.