Reusable means you don't need to build a new one (although the shuttle experience shows that in many circumstances like heat shields it's as expensive to refurbish as to build de novo)

Recycleable means you can salvage the original materials and use them again for something else. Many recycling processes are as expensive (or more) than digging new stuff out of the ground.

The main value of recycling is reducing the sheer volume of garbage.

[I send packaging materials for recycling, burn scrap timber and coarse card for warmth, and compost all foodstuffs. That means I would only need to put my garbage out every 4 weeks, instead of once a week - except in the summer when 2 weeks is the limit for health reasons :-)]

When you're building high-value items like spacecraft, it's worth having high-quality materials in them.

One day when spacecraft become as commonplace as automobiles, perhaps there will be as much recycled material in them as in automobiles (currently <20% worldwide)?