MOBILE_CONVERSION values are always related to the timeframe specified by the campaign, and LIFE_TIME_VALUE_MOBILE_CONVERSION is basically the entire aggregate data from the Mobile Application Conversion Tracking partner the account/app is set up to use.
The Lifetime Value data is meant to track Twitter-acquired users across their entire lifetime. Meaning that if an install was attributed to Twitter, you will see all conversions for that user on a campaign level, even after the campaign has ended