alright, teach me???

I got the s&w model 438 .38 special. First let me say i love it!! I stink at shooting but am actually decent with this. weapon. That being said i know It shoots. 38 or. 38 +p loads but wat kind exactly are +p???
I have 3 boxes ive been toying with. 1 is Remington 130. grain, 2 is ultramax 158 grain wadcutters and 3 is federal 158 grain.
Is + p a special type or wat? I'm just confused a dab. I noticed that most 357 loads seem to be less grains than my. 38 but the 357 is supposed to be a bigger more lethal round???? I can tell ya these 158 grain loads do damage. Tnx for any clarifications. Hg

+P ammo says +P right on the end of the box, they are just loaded to a higher pressure than the standard ammo

Speer factory loaded GDHP's 125 grain.
The 357 magnum has more than twice the muzzle energy over 38 special+p in general. In my experience when a rifle or pistol cartridge is denoted as "magnum" it means it.

Velocity(in feet per second)Muzzle 945; 50 yards 891; 100 yards 845.
Energy (in foot pounds) Muzzle 248; 50 yards 220; 100 yards 198.

Velocity(in feet per second) Muzzle 1450; 50 yards 1261; 100 yards 1118.
Energy (in foot pounds) Muzzle 584; 50 yards 441; 100 yards 347.