Fender Blues Junior
I will not focus on make-up variations here. It really doesn't matter much. But I can't be quiet on speaker variations. One more thing to note, in 2001. production of these amps moved from USA to Mexico. Early models of Fender Blues Junior were a bit moody or bassy if you like, and later models were more bright sounding, similar to the great Fender Blues Deluxe.
Standard Fender Blues Junior Uses Eminence speaker. It sounds perfect with Telecaster and Stratocaster guitars, but it's a bit bassy for my taste when Gibson guitars are plugged into it. As of lately, Fender released new edition called "Blues Junior III", which replaces the standard one. It has minor changes over the last one, like front reading text on top panel, new badge.. etc.
NOS Lacquer Tweed Limited Edition Fender Blues Junior Features Jensen C12K speaker. It's much brighter than the standard one, but it very much depends on what sound flavors you prefer. To me, it's too bright when played with Telecaster or Stratocaster type guitar, but sounds really nice with Gibson Les Paul and other Gibson guitars.
Tweed Relic Edition Fender Blues Junior This one is pretty much the same as the one above, but it's factory aged and features Jensen P12R speaker.
Fender Blues Junior Texas Red Features Celestion Vintage 30 speaker. I think this one is actually the best Fender Blues Junior edition produced to date. This speaker is the most common upgrade everyone will suggest you. It just sounds right and powerful. You can play both Gibson and Fender guitars through it, and it will deliver everything you wished for!