Hello friend ! Well .. سوا and مع بعض almost have the same meaning سوا = Together مع بعض = Also together BUT .. !!!!! The word ( مع بعض ) Can be used for ( Together ) and ( All together ) I MEAN We can use the word مع بعض for ( 2 person ) AND for ( more than 2 person ) . but سوا only used for ( 2 person ) I'll give you an example : Lets go all together = خلينا نروح مع بعض Lets go together = خلينا نروح سوا = خلينا نروح مع بعض SO SHORTLY !! مع بعض MEANS Together and its used for ( 2 or more person ) سوا MEANS Together and its used for ( 2 person) I hope if I helped you :)) and If you didn't get I can explain more :) For sure sister this is not Classical Arabic.but for learning you should learn classical Arabic :))

they both have the same meaning .. but you سوا usually used in an informal way specially with friends and couples , مع بعض its used generally . and both can be used for 2 persons and more ... im Egyptian :P so i know what im sayin :D , p.s you will find many words that have the same meaning its just the richness of Arabic can make for the same meaning different words ;) , good luck with arabic , for any questions just send me a message