I would like to understand the difference between a cross-country (XC) mountain bike and a "trail" mountain bike. I am looking to upgrade to another hard tail. Trek and Cannondale have these two designations, but Scott does not. I currently have an entry level Scott and really like it but looking to upgrade (likely to another Scott bike). Is there a difference in speed and weight or is this just a marketing gimmick? Will an XC bike hold up on trails?