previous answer is right. go to investorpedia and type both of them in to see
how they are calculated differently. the quick and dirty, EMA's are going to
respond quicker to recent price change, where as SMA's, if you use a 50 day SMA,
it will weigh all days equally in importance.

there is also weighted MA's, which are even faster than EMA's.

im not sure what you mean by line 2 and line 3. might be specific to your
charting program. could just be the thickness of the lines. but i wouldnt know
off the top of my head.

simple moving average, exponential moving average