Welcome to FT and the UA forums!^ Please take a look through the UA FAQ sticky at the top of the forum. There you will find more information than you can imagine on all things Mileage Plus and UA related.

To elaborate on what was already posted by Diplomatico, your EQM's keep track of your annual miles flown on UA and UA partners. This figure is actual mileage only unless you receive a CoS bonus from a premium fare ticket. It would also reflect any EQM's earned through other means (Chase CC bonuses etc.).

The EQS keeps tally of every flight segment you have flown and is another means of reaching Elite status. It also resets on 1/1 of each year.

Lastly, your Lifetime United Flight Miles keeps track of all the actual miles you have flown on United airlines planes ONLY. The only pertinence of this figure is that if you manage to fly a million miles you will receive "Million Mile" status which equates to Premier Executive status for life, regardless of how little you fly. If you read through the FAQ's you can find the rest of the info on this.

Craig