I'm running Mac OS X Yosemite. There are multiple administrator accounts in my Mac. I don't want an administrator to snoop into another administrator's account. Is there any way I can prevent an administrator from resetting the password of another administrator account?
The simple answer is no.
Best practices on multi-user Macs dictate Standard accounts for all users, with a separate administrator account setup for maintenance work (software installs and/or updates, etc.) The philosophy is that with great power comes great responsibility, and an innocent mistake can cause havoc.
Daily use of Macs (and PCs for that matter) do not require the elevated privileges granted to a administrator account. At home, for example, I've created two admin accounts: one for emergencies, and my own account. Three other accounts: for my spouse and 2 kids, are Standard. When my kids are old enough to have their own Macs, they'll have only standard accounts, too, with a separate admin account for maintenance & whatnot. When they make enough money to purchase their own Mac, then they can decide how secure to make them.