One can't make generalizations and say .357 vs. 38 special +P. It really depends on the particular load that you are shooting as well as the firearm it is being shot out of.
As an example, Sturmpanzer says he is shooting 125 grain Golden Sabers. His old gun was the Rossi I guess. But for comparison sake, lets take Lucky Gunner's actual testing out of a 2" snub. The first chart shows the results. I'll be generous and say the average is 1100 fps with the 125 grain and that equals 336 foot pounds ME. (I know ME is not everything, but it's good for paper comparison for our debate).
Now say I'm shooting Buffalobore heavy .38 +P LSWCHP out of my 1 7/8" LCR (and yes I have shot it).
https://www.buffalobore.com/index.php?l=product_detail&p=108
Their site says:
➤ 1040 fps (379 ft. lbs.) -- S&W mod. 60, 2-inch
➤ 1059 fps (393 ft. lbs.) -- S&W mod. 66, 2.5-inch
➤ 1143 fps (458 ft. lbs.) -- Ruger SP101, 3-inch
➤ 1162 fps (474 ft. lbs.) -- S&W Mt. Gun, 4-inch
And that is what I got with my own chronograph or pretty close to it.
THIS IS VERY CLOSE TO THE ORIGINAL FBI LOAD.
Now, according the the ballistics calculor, that equal 380 foot pounds ME.
The heavier BB .38 special +P is hotter than the 125 grain .357 golden saber which is consider a medium of the road round.
Now, to be very clear, I am not saying that .38 special equals .357 by any stretch of the imagination. And I even cringe everytime someone tries to point out that since you are shooting .357 out of a short barrel revolver, the .357 looses so much that it's equal to the .38.
I'm just pointing out that it all depends on what load you are choosing rather than .357 over .38 special.
SORRY FOR THE LONG WINDED POST!