The factory fitted strings are D'Addario EXP coated strings in the gauges:
1st: .012; 2nd: .016; 3rd: .024; 4th: .032; 5th: .042; 6th: .053. This is available as D'Addario EXP11-Light - all the info is here:
http://www.daddariostrings.com/DADProdD ... Class=BBMA
You can also use mediums (0.13 - 0.56)
The differences in the Avalon range are many and varied. Over the years, the guitars produced in the Newtownards factory were subject to approved modifications originated by the luthiers now designing and building Avalon’s. For example, the bracing profiles were modified and a major improvement to neck stability was made by using a bi-flex truss rod rather than the unidirectional single flex rod. These modifications were transferred to the Legacy Series. When Avalon was birthed, the body shape dimensions were revamped and the cosmetic detailing was approached afresh to create a distinctive look. Perhaps the most significant design differences concern the neck width and bridge system; in response to players comments, the neck width was narrowed by 1mm and the action lowered a tad. The bridge system used in Avalon’s is pin bridge rather than the classical type through bridge. The pin bridge accentuates the rake angle of the string over the saddle, delivering more power and projection. Add to this the innovative "AXX" bracing style used on Avalon Gold and Silver range models which produces a bright, consistently balanced playing tone.
Steve Mac