solid colour: you cannot see the grain of the wood thru the colour coats. its like house hold paint ... generally used to hide bad quality timber transparent/ seethru colours: they give a slight tint to the colour of the wood but mantain the transparent laquer type quality, i mean, u can see the grain of the wood thru the colour. ... ummm lemme see if i can find good examples. ..
i have all three types: solid: on my gibson classic, its black, solid, boring colour, but no complaints...its a gibson for god sake! transparent: another les paul, but not gibson, a custom built one, i have a sunburst on it (check https://indianguitartabs.com/showthread.php?t=6341 ) ...thats transparent. metallic: the third one is the baritone (searc the post your guitar pics thread ... i have a pic of that guitar there, its red metallic). but i prefer the transparent ones,