Weapons and armour are organised into five tiers. Higher tiers have better stats and need more advanced materials to craft. You can read an item's tier at a glance from the colour of its icon outline — it's also noted in the mouse-over tooltip:

Each nation has its own gear set in every tier — and because stats are standardised within a tier, you can collect, craft and wear any nation's gear regardless of your own. The look changes from nation to nation; the numbers don't.