If you run under any regulation (PCI-DSS, HIPAA etc.) your PC will have to be hardened, have anti-virus, full disk encryption, 2 factor auth for remote connection and tick every other possible "security" box to be compliant.
Mobile well it's easy just have an MDM and do what ever the fuck you want, so if you want to use your laptop from the train in a regulated industry you'll have to stand on one foot, hold the laptop over your head while giving a blood sample to authenticate you and on the other hand you can just hope on your tablet/mobile phone connect to your office using VPN on-demand or even a regular web app (as long as it's SSL because dur-dur security!) and you're golden.
HIPAA endpoints that are used to access, view or input patient data are in scope.
I am a QSA.
A better alternative in a laptop form factor would be a zero client laptop, but they are very niche devices.
I didn't really go into detail about the full use case, they get other benefits from the overall snappy iPad experience in terms of switching apps, etc.