The two are light years apart. Far more than the 1mm numerical difference. The standard 9mm load of a 115 gr JHP of FMJ at 1200 fps or so is a minor caliber round. 9mm's can run from 90 gr up to 147 grains. 950-1400 fps.
The 10 mm is a major caliber round. Standard load of a subsonic 180 grain JHP @ 1000 fps is designed to replicate one of the better .45 ACP loadings. the 10 mm can be loaded with bullets as light as 135 gr @1500+ fps up to 180 gr JHP's @ 1300 fps. With that load it will exceed .357 magnum capabilities and approach many .41 mag loads.
The 9mm is a fine defensive round for a concealed handgun. The 10mm is a powerful cartridge for a full size pistol, not for the faint of heart.
I have both and they each have a niche in my carry selection.
When my son-inlaw got his CCW permit he ask my advice and I said nothing less than the .40 S&W. Personally I like revolvers and go with the PD 329 S&W. That`s a supper lite .44 mag., but what it lacks in weight it makles up for in recoil. But I really don`t mind it as I like to know I`ve only got to hit them once.
The Colt auto's in 10mm tend to be under sprung ie they need a stronger recoil spring to reduce the battering. With recoil springs strong enough to handle the high powered loads, the Colt's do not run well with the FBI "light" ammo. Go with a "Sprinco Recoil reducer" they will keep the slide from battering the frame. My 1006 sports one and runs great.
A DE 10mm for $650? That's a steal. Even though I do not care for the DE.
That was a good year. It was before 2008 and what we have now.
I can undeniably state that two dead home invasion robbers my Son killed with his Browning High Power 9mm +P loads are still very dead.
One bled out, the other got his heart blown out of his chest.
The third one ran faster than his friends. He's doin 8 years in Folsom Prison.
The Son was cleared, Self defense.
That Son is doing 15 years for 2nd degree murder in a fight 4 years later. Cut some guys throat. The Dumb ***!
9mm? Or 10mm?
Neither, if you can't hit where you are aiming. Either one will kill real well.
Just the facts.