There are differences, and some of them are more clear than the others: - Many blazers have gilt, silver, enamelled or other metal buttons. This is the main difference - A few have embroidered club (or invented club) crests on the breast pocket - Patch pockets are more common on blazers, although they can be found on many suits as well, of course - Blazers can come in cloths that are quite a bit rougher - They can also have slightly different cuts, often being shorter To add to the incoherence, there's also a somewhat obscure historical difference between single- and double-breasted blazers, to do with which types of clubs had single-breasted ones, whereas the double-breasted blazers are supposed to be descended from a naval uniform. And then there's the caricature-ish English rowing blazer, with white or coloured edging on lapels, quarters and pockets, or with bold stripes all over. There are big differences between countries i how blazers are used and looked upon: The English tend to think of them as something for schoolboys and old middle-class men, at least outside of a clubby context, whereas Americans see them more or less as the core of Trad dressing. In southern Europe, particularly France or Italy, navy separate jackets with regular buttons are worn for business frequently. In northern Europe, I think the attitude is more mid-atlantic; blazers are more common, and more liked, than in the UK, but less so than in the US. I think an odd navy jacket, whether it's bought as an odd jacket or is what's left of a suit, is extremely versatile. If you want to use it like a blazer, you'll probably be best off with a jacket with no discernible pattern in the cloth, i.e. no stripes, weaves etc. That said, I have a navy suit with a slight herringbone weave in the cloth, and I like to wear it with jeans or grey odd trousers. I also have a full-on navy double-breasted blazer with antique military buttons that I had gold-plated. (Daks, very pinched in the waist, tight-fitting and short.) I almost never wear it.