Futsal has always been classified as the little brother of football, but it's not exactly like that. The dimensions of the field, the composition of the ground, the type of line-up and the number of players have an influence on the game. These are the main reasons why futsal should be considered as a sport apart.
The first sign of distinction between futsal and football are the futsal boots. In futsal you won't need boots with studs but the sole of the boot has to be plain and adherent to the surface at the same time. Normally surface is hard ground.
The rules of this sport differ from those of football because it is played 11 against 11 on artificial grass but it's not only because of the different surface but because of the constant movement of 4 players that run across the whole field and swap positions. Although they have basic roles, that become clear at the beginning of the game, futsal players have to interpret more roles.
Changes between holders and substitues are fundamental because of the effort it takes to cover the whole field or attacking and defending in few seconds. That's why it's better to make the ball run and not the players.
Because of the reduced dimensions of the field and the missing of an offside, the teams are more organized and spaces are more closed than in football. Therefore it is important that players touch the ball a lot because kicking out the ball is necessary to break the rival defense.
It's not a casualty that the best jugglers are futsal players that have to face a lack of space and have to emphasize creativity in movements where there's almost no space and where the speed of running is essential.
Nike Mercurial victory III CR IC, modern boots
Adidas Janeirinha sala, casual and comfortable