For The Most Part

All versions of Minecraft are for the most part the same with some exclusives.

(Note: This list ignores the whole Render Dragon thing going on because it's changing right now and not especially worth noting for this question.)

Every Version...

• All editions have a slightly different world generation than another. This often goes unnoticed but still exists.

Windows 10 Exclusive

• Windows 10 is the only Bedrock platform that supports the Bedrock JavaScript API.
• Windows 10 is currently the only platform that supports raytracing.

iOS "Exclusives"

• .mcworlds, .mcpacks, and .mcaddons got changed a bit ago in an iOS update where you can't directly run them without a share method (i.e. a special map/addon app, not Safari/Files Viewer).
• Thought I might include this: iOS often has more patches than the other versions, which causes them to run on a higher patch while still being cross-play compatible.

Console Exclusives (Playstation 4/5 / Xbox One / Nintendo Switch)

• None of the console editions of Bedrock allow you to connect to just any Bedrock Servers, only allowing access to “Featured” servers. For example, you cannot play BrokenLens on a PS4 but you can play The Hive.

PlayStation 4 Exclusives

• PlayStation 4 can use a PlayStation Network account to play with other PlayStation users, but to play cross-play one must sign into Xbox Live.
• PlayStation 4 has the option to go into the PlayStation 4 Edition before it joined Bedrock Edition, which is the same as Legacy Console but updated to Village & Pillage. This is great if you miss the old minigames on legacy console, like Glide (Elytra Course), Battle (Survival Games), and Tumble (Spleef). Sadly now that Bedrock exists there are few people playing legacy PS4 Minecraft minigames to play with.

Are these Major?

No, with the exception of the Legacy PS4 Option.

• World generation is so slightly different and is rarely different in the first place.

• The JavaScript API is rarely used because it is extremely limited and commands are more fun to use anyway.

• Raytracing is supported by graphics cards that most people don't have, so most Windows 10 users can't use raytracing.

• The iOS files not working without sharing is annoying, but not too big of a deal since most iOS users use apps to get packs and worlds anyway.

• iOS patch thing doesn’t affect gameplay at all.

• The featured servers are the most commonly played servers for Bedrock, with very few getting a player count even close to the featured ones.

• All the PlayStation/Xbox Live account situation does is force PS4 Minecraft users to make an Xbox account for cross-play and server-play.

• The legacy PS4 option though is probably better to remain a PS4 exclusive, since it is mainly for nostalgic and minigame purposes. Also, if everyone could play PS4 minigames it would just turn into the PC players destroying console and pocket players again.
  Not to mention that there would probably be legal issues porting 4J's game to all platforms (I'm no legal expert and not pretending to be one), and not a task the Bedrock team would want anyway, this was likely an option after Xbox users refused to update to Bedrock. They likely wanted to reduce community backlash as well.
  

If I left something out please comment/edit.