If you notice, the bottom of the lifetime mug is not removable and, IIRC, it was made by the Thermos company for Disney.
The later, squatty mugs, had removable bottoms so they could go in a top rack of a dishwasher. Those mugs and the tall skinny mugs were sold as length of stay. They are branded "Made in China".
Each resort eventually had their own resort branded length of stay mugs, both tall and squatty. In 2007 Disney quit selling resort branded mugs and just sold the same mug in every resort. 2007 the mug had the year printed on it. 2008 was the same designed mug as 2007 but with no year on it. 2009 brought us the red mug with the Disney characters, and 2010 was the same mug as 2009 except it is shaped a little differently. There is no "flange" about 2.5 inches from the bottom to accommodate a cup holder.
Mug history at its finest!