And there's more. One wavelength (or a mix of) can be seen as different colours and the same colour can be many wavelengths, depending on context. Remember when you painted a room. The get some colour charts from the shop and are amazed at how different they look at home. You then decide on a colour and paint the room, and again are amazed that it doesn't look the same as you remember the chart looked. This is called "colour constancy" and is why we need white balance on a camera. The camera sees wavelengths or mixes of them. We see colour! That is different. It is an amazing world we live in, and we are amazing animals.