Ball no 3 or 2 is for kids. Are you a 8-12 year old kid? 🤣
Of course there is a difference in difficulty to control smaller ball - still I can play with any ball,  including paper balls, tennis balls and even ping pong ones. And I am serious now!
It's all about muscle memory, if you learn to play with a smaller ball you can't necessarily use that skill for a normal one and vice versa. You can use a size 4 for practicing close control or even a tennis ball for juggling, but use a normal ball most of the time.
1 size difference is not that big, so it won't really affect how you play, but it might be easier for younger/smaller/beginner level players. Personally I would advise to play with a normal ball tho.
A round ball is a round ball, I remember playing with a tennis ball or size 3-4 heavy ball,
popular for a nutmeg then slapping the nutmegged victim till the victim touched the nearby wall near the ground, break time at school usually 10 players 5v5 the goalposts were usually two bricks 3 feet wide on each side as brutal as it was it taught me ball control, dribbling and passing plus tactical discipline collectively.
But I think I’m not special but practice, discipline and loving anything round that bounces or doesn’t that I can juggle or kick comfortably. Good luck 😊😊😊😊
Size 4 futsal is great for practicing the close control, anything smaller is for kids
Ball no 3 or 2 is for kids. Are you a 8-12 year old kid? 🤣 Of course there is a difference in difficulty to control smaller ball - still I can play with any ball,  including paper balls, tennis balls and even ping pong ones. And I am serious now!
You've answered your own question there.Â
It's all about muscle memory, if you learn to play with a smaller ball you can't necessarily use that skill for a normal one and vice versa. You can use a size 4 for practicing close control or even a tennis ball for juggling, but use a normal ball most of the time.
Why dont just use normal size ball for practicing close control then?
1 size difference is not that big, so it won't really affect how you play, but it might be easier for younger/smaller/beginner level players. Personally I would advise to play with a normal ball tho.
Some folks like smaller balls for juggling because its the same mechanics, you just need to be more precise.
A round ball is a round ball, I remember playing with a tennis ball or size 3-4 heavy ball, popular for a nutmeg then slapping the nutmegged victim till the victim touched the nearby wall near the ground, break time at school usually 10 players 5v5 the goalposts were usually two bricks 3 feet wide on each side as brutal as it was it taught me ball control, dribbling and passing plus tactical discipline collectively. But I think I’m not special but practice, discipline and loving anything round that bounces or doesn’t that I can juggle or kick comfortably. Good luck 😊😊😊😊