In my experience it depends on several factors...gender, muscle type, definition of "easier", level of conditioning, preferences and amount of time one can spend resistance training. Personally, I have found it easier to achieve toning but I am a 6' tall woman.

This depends on a lot of variables. For people who have high metabolisms gaining even a pound of muscle mass can be a huge task. For other such as myself I can put on muscle mass but its very hard for me lean up and get toned. All you can do is tailor your approach to what you are trying to achieve. I firmly believe is this:

For muscle toning - high reps (12-24) with lower weight

For increasing mass - lower reps (2-12) with more weight

There are a million opinions out there but this one seems to be pretty universal in the fitness community.