As far as mentors, both programs are roughly the same. Although CareerFoundry has been a little strange lately in that I have had 2 new mentees whose previous mentors disappeared. I don't know if it's an isolated incident or something is going on.
As far as portfolio/coursework, you get more portfolio work out of UX Academy as they have more projects. With CareerFoundry you just do one project all the way through following a specific iterative design process.
Both are about the sam eas far as exposing you to new tools. CareerFoundry might be a bit better because they suggest tools, whereas UX Academy lets you choose your own. However, UX Academy gives you a student discount on Sketch and CareerFoundry doesn't do that.
UX Academy you would be exposed mostly to Sketch and InVision, plus anything else you wanted to use.
CareerFoundry uses UXPin, InVision, and Google Analytics (for one assignment).
I'm not sure about the business connections and how employers view the certification. There is no standard UX certification and there are many options out there so it might just depend upon what you are looking for. I do know that HFI, Neilson Norman Group, and Cooper are more respected in the industry, however, none of those places offer online training.
As far as I know, neither of the places offer tools to launch your own career. Also, the job placement they both talk about can be contract work, freelance work, part time projects, etc.
Let me know if I missed anything or if you have other questions.