Regardless of the type of blend (blanc de blancs, blanc de noirs, blend of three grape varieties, rosé, etc.) or the dosage (brut, demi-sec, extra-brut, etc.), the difference is very simple:
A non-vintage champagne is made from wines from different harvest years, and this represents the vast majority of the region's production. There is no year printend on the bottle.
A vintage champagne is always made with grapes from the same harvest. The year of the harvest in question is always printed on the bottle.
At Champagne Pierrel, we produce both: our Brut Grande Réserve is a non-vintage champagne, our Brut Blanc de Blancs is a vintage champagne.
You probably have other questions; here are our answers in the following links:
What is the difference between a brut and a demi-sec?
What is the difference between a Blanc de Blancs and a Blanc de Noirs ?