Is there a way for locking the screen and putting it to sleep/activating the screen saver to be two different events on a MBP?
There are a number of posts (here and here) on superuser.sx. 


To lock the screen (actually invoking the "Login Window…" action from the User menu, and a direct analog to the Win+L shortcut in Windows):

/System/Library/CoreServices/Menu\ Extras/User.menu/Contents/Resources/CGSession -suspend

To sleep the display (I use this all the time as part of my last command before bedtime on my home machine):

pmset displaysleepnow



Either of these options can be invoked through a keyboard shortcut by tying a shell script to a shortcut (using Automator (like this), Quicksilver, LaunchBar, Alfred, etc., see this post). 

It's worth noting that BetterTouchTool can also perform these actions (directly mapping shortcuts to actions like this), as noted in this answer to one of the prior questions). The developer has been giving the app some love recently, which has been wonderful to see.