How to learn the different types of rock
The best way to learn about rock types is to handle rock specimens guided by an experienced geologist.

By handling rock specimens you get to feel the weight of the rock, its roughness or smoothness or if it feels slippery, soapy, glassy, firm or crumbly. Is it weak or strong? You will also be able to better see the colours in the rock, the sizes of the grains of minerals, the way the rock breaks, its cleavage. You can test its hardness. If you have a piece of unglazed white porcelain you can do a streak colour test.

All these sorts of things can help you identify different rock types.

Also, the same rock type can look slightly different in other parts of the world, because of geological and environmental processes that rocks experience in different parts of the world. This is particularly so if the rock is deeply weathered.

Learning the different rock types, alone from books and pictures is a difficult way to learn, befriend a geologist, you'll learn more quickly and it will be more enjoyable.