If a guy and a girl hang out all the time but aren't boyfriend and girlfriend, they'd describe their friendship as platonic.
This word platonic refers to the writings of Plato, an ancient Greek philosopher who wrote on the interesting subject of love.
My maid of honor at my future wedding is probably going to be a guy, who, for all intents and purposes, was the first love of my life. Both MUST be standing next to me on my wedding day. Here's the difference, though: One is platonic love, and one is romantic love.
He's my best friend and has grown with me in a way only someone who has been around me since day one could. Then, there's my boyfriend, who will be the groom... Let me use the tiny part of my brain that can comprehend something like love and do my best to break down this difference: When you love someone platonically, there is no fear in conflict.
People in a platonic relationship may be exceptionally close but there is no physical attraction between them.