I am returning to d&d after several years and was wondering is there some site that contains a list of what changed between editions
You could usefully compare 1e and 1.5 (changes wrought by the 1e Unearthed Arcana), changes between 1e and 2e, and between 3e and 3.5e. Even those lists would be fairly extensive, but they would be short enough to make a useful comparison.
But the changes between most editions are so massive that they are practically speaking entirely different games. Third edition, fourth edition, and fifth edition each brought about massive changes compared to the prior editions, so much so that it would be a much more useful list to compare what has remained the same between editions. But even things like "what is a hit point, and what does it represent", have changed in important conceptual ways between editions.
Generally speaking, 4e represents the most massive outlier and will feel the most unfamiliar to someone coming from one of the other editions. The other editions can conceivably play something alike despite all their differences, so that I feel fairly sure I could run 1e, 2e, 3e, and 5e in a common style. But there are large differences between them nonetheless.
1e: Eclectic, arcane, stacks of independent systems. Obvious legacy in tabletop wargaming. Very much mix and match rules, often poorly understood by the tables that used them, and as such almost every table plays with a different subset of the rules, using different simplifications to speed play. Very high reliance on DM adjudication by fiat, leading to an intensely important metagame. Rules in the DMG assume a Gygaxian dungeon/haven setting is the norm, and that the purpose of play is developing player skill. Later rule books begin to subtly alter the game by adding new modular stacks of rules.
2e: Attempts to unify, codify, and simplify the 1e rules systems while retaining much of what makes them by then familiar. Fewer examples of rules that are one offs, as can be seen in how dragons are treated differently between the two systems. Initiative is overhauled, NWP's become a standardized part of the core rules, bards are in as a core class rather than a pseudo-prestige class, but paladins and barbarians are out. The rules in the DMG assume no setting, and that the purpose of play is creating a story.
3e: The 1e flavor is restored - barbarians and paladins are back in, and the core spell list will look very familiar to anyone who played late 1e. But the game's engine is tweaked to become a universal rules engine, along the lines of something like BRP or GURPS. Fallout style 'Feats' appear as character building options. A true skill system replaces NWP's and silo'd skills like thief abilities. Some classes like 'thief' and 'ranger', get slightly more generic incarnations. Sorcerer makes an appearance as a qausi-Vancian core spellcaster class. Monsters begin to use the same basic rules that apply to PC's, and acquire strength, constitution, and other ability scores, skills, feats, and so forth. The DMG rules assume something somewhere between the 1e and 2e assumptions is going on, largely a series of tactical skirmishes joined by an overarching narrative. However, the game is much more Player centric compared to prior versions, with the assumption that a large part of the game is planning and tweaking your character build. System mastery becomes as important or more important than Gygaxian style "player skill". The rules will get officially overhauled as 3.5e, which will bring massive amounts of rules bloat and optional rules, and further the player centric nature of the game.
4e: D&D as reimagined by someone that hated D&D. Virtually everything except the core ideas of the game is tossed out. Strong influences from video game innovation, particularly Blizzard style games like Diablo and World of Warcraft. But also strong conceptual influences from FORGE and Indy gaming, particularly the idea that a game system can only do one thing well and can only support one type of play, and so therefore systems must be unified around achieving this core idea of their gameplay. Very strong reaction to the general poor balance of 3e resulting in all classes sharing unified design concepts, which can be thought of as "everyone is a spellcaster" and "spells are powers/powers are spells that you use to overcome combat obstacles". Classes are reimagined as primarily pawns with tactical roles in a table top wargame, with non-combat activity being left largely to the fiat of the DM. Tons of new classes are introduced, each with their own spell/power list. The DMG assumes that players will largely want to be doing at high level basically what they were doing at low level. Completely abandons the idea of NPCs using the same rules as PCs.
5e: Almost complete rejection of the 4e approach in favor of streamlining 3e. Arguably, is conceptually to 3e what the BECMI rules were to 1e, in the desire for a simpler and more approachable game without some much of the arcane subsystems that could get in the way of DM adjudication. Attempts to fix the spellcaster/non-caster balance issues by massively reducing the power of spellcasters at high level. One area of 4e that is partially retained is the idea of NPCs and PCs using the same rules, as 5e adopts a moderate position between that of 3e and 4e on the subject.