3 interesting chats on ths topic so a wee piece on the key differences. Most amateur triathletes record slower times in OW than in the pool ( there are always a few exceptions to prove the rule).
This time of year the main issue is rubber overload. Winter suits, rash vests, gloves, hats and booties are all needed when the water temp is sub 10 but basically the more rubber the slower you are. Hats and rash vests provide more buoyancy the wrong side of the hips driving the back end down. Add in boots and the water fill and reduction in ankle flex adds a nice draggy anchor. Strip those away and the wetsuit often produces a positive impact on body position for most.
Gloves are interesting. If you have smaller hands and can get tight fitting gloves without them filling up with water then you are swiiming with paddles. If that gives you a hold on the water and lower more powerful pull that can actually be a benefit..which is why they arent allowed in most races. For most though gloves kill your feel for the water and get heavy when wet or full of water. Lets say its 100g per hand...at 60 strokee per minute thats a fatigue inducer right there.
So as the temp comes up..shed the rubber. For me thats around 20 secs per 100m.
In the pool some people are super slick at button pressing and in short intervals with plenty of recovery...thats 'fake fast' so as the rep distance goes up..the speed is more realistic.
When in the pool we are at our fastest when coming off the wall and if you turn well and maximise the momentum that will always be quicker in a pool. If you turn like a supertanker the difference out and in will be less marked.
If you think your pool speed is say 1:30 in sessions with reps and you do ow with 500 or 1k stretches and thats 1:40... try swimmimg a 1k in the pool and the times will be closer.
Then we have stroke imbalances. If you have a pull to one side then having to correct means more frequent sighting and more disruption to the bodyline. If your sighting technique is poor..thats a double dunt!
Lots to play with!