Yes, the standard finish Axioms use a high-quality vinyl application to MDF substrate. The real-wood versions use a real wood veneer applied to MDF.
The vinyl standard finishes are very impressive, difficult to distinguish from the real-wood veneers except on close inspection. They even have a wood-like texture when you touch them.
Your first Axioms, I suspect, use a real wood veneer applied to MDF. To my knowledge, Axiom always used MDF enclosures, with either real-wood veneer or a vinyl overlay. MDF is acoustically opaque and non-resonant, or as close to that ideal as possible and the material is very consistent from one sheet to the next. You do not want speakers actually made of real wood, because they resonate (vibrate) far more than MDF, and the enclosures would contribute audible coloration to Axiom's neutral sound quality.
Axiom Resident Expert