Is teaching English to adults easier than teaching to younger students?
That depends on you as a person and as a teacher. Some people find they relate better to children, others to adults. Personally, I find children far more difficult - I have to put a lot more effort into preparing interesting activities for them.
Is it harder to enthuse elementary adult students in the class room?
Once again, it depends on your personality. I find that I can have fun with adults at an elementary level. If I have fun with young learners, I risk chaos. But that's a personal answer.
can you use the same methods to motivate younger students?
No. But that's a VERY general answer.
I think it would be quite tricky to communicate and teach adult learners at a beginner level without sounding patronising.
I have done some apparently very childish things with adults, and they have thoroughly enjoyed them. Yet again, it's a matter of personality. So long as you believe in what you are doing, have enthusiasm, and can convey that enthusiasm, most adults can sense this. However, if you play a game just because you have been taught on your CELTA that you must keep learners active, this may well not succeed. Try to be sensitive to your learners' reactions. If they appear uncomfortable, switch to something else.