What's the difference between a blazer and a suit?

The number of buttons and the occasion where it was worn. Don't laugh about the buttons, I have an article from 1926 decrying modern men wearing the wrong number of buttons to the office! Let's go back to the twenties when these distinctions of dress were quite important for every well dressed man to know. Blazers were originally emblazoned with a badge or patch from a private school or club. They were usually navy blue, or the official colour of the club school whatever. Now it means a solid colored jacket, three buttons in two rows (double breasted) worn with non-matching pants. A sport coat was distinguished from a business suit or formal suit by having three or more buttons in the front and a looser fit, There would be pocket flaps, extra pockets, and top-stitched details. The sport jacket was also made in colours such as white, beige, stripes, light blues, pale greys and browns, and others.  more