Difference in Ruger Models MKIII

I am new to Rugers (and handguns) and I was searching and came across this model Ruger Mark III 22/45 Bull Barrel 5.5" Pistol 10 Round Blue

Other than barrel length, what is the difference with the pistol on kygunco.com and the current models on Ruger® Mark III™ Standard Rimfire Pistol Models




Any insight would be appreciated.

Thanks!

I shoot the Ruger P95 9mm love it.

22/45 has adjustable sights and a polymer lower while the Standard has fixed sights and a steel lower. Grip angles are different as well.