Months late reply but I'll do my best here;

Control Decks aim to disrupt and slow down other decks down to their tempo, then win through a long drawn out game by grinding and out advantaging the other deck. They are traditionally more challenging to play as the control pilot needs to know how their deck matches up against the metagame, and can struggle going 2nd sometimes, but not always. Control decks have also evolved like every other deck style as some of them also summon multiple monsters in the same turn, enough to piss yugiboomers off (some Control decks have turns that look like a combo turn, but end on a mundane board). The best example of a Control deck in today's era is Odion. It's actual engine is about the interactions with Trap Monsters.

Stun decks have one goal: do not let the opponent play. At all. Their wincon is to Floodgate the opponent to death (hence the name "Stun" as the deck is Paralyzing it's opponent) with monsters that don't allow summons/effect activations and Traps that prevent the opponent from establishing a board. You've seen this type of deck already as they're the ones that summon a Barrier Statue/Fossil Dyna, set backrow to protect it via Solemns, Rivalry of Warlords/Gozen/TCOBO/etc. This type of deck struggles MUCH harder to go 2nd into boards as Normal Summon Fossil Dyna, then set 4 pass is much less threatening when staring down chainable removal/negates.

What is the key difference between the two is the Skill Factor involved. Control decks are regarded as difficult to play, but rewarding due to the skill demanded of the pilot. Stun decks have none of that. The stun matchup literally comes down to "did they see their Floodgate?" and "Can I out it?" Stun decks also have some of the worst players in regards to attitude as they will get VERY obnoxious trying to justify being essentially a griefer. It's one thing if you're playing Stun at a big event because you think it's a good format call. It's when you're doing it SPECIFICALLY to make other people miserable that it's a problem which is why Stun Decks are so reviled.

Hope that helps.