What is the Bg2 difficulty equivalent of the first game?
Is it normal or core rules ?
I want to play it at the same difficulty as the first game .
Is Core the same or normal ?
Or would you recommend Core anyway?

core rules is normal tabletop rules and the baseline... BG1 and BG2 are about the same, yes the monsters are harder but you should have leveled up a bit as well

if this is your first play then I'd start at core... you can always lower it later

Thanks A lot ! I just read the description it said core was the same as in BG1 , I will be playing at Core then!

Core rules is basically the "authentic D&D experience", as per the rulebooks. If it's your absolute first time playing a Baldur's Gate game (or a D&D CRPG in general), I would recommend starting out on Normal until you get a solid understanding of the game's mechanics and how combat works, but there's nothing wrong with diving straight into Core difficulty too. :) As you get more experienced with the game, feel free to try out the harder difficulty settings if things start feeling too easy. If that STILL isn't enough of a challenge for you, there are difficulty mods like SCS out there that will crank things up to 11 and beyond.