These are 4 different kinds of crates. There are models of 2 major types of crates – Wood and Metal. Wood crates have a poly count of 78 and 2 versions – closed and one with fruits. Metal crates/boxes have only 6 polygons and are of two types – closed hard metal box and radio-active/futuristic box/container.
The models are kept to minimum but a lot of work has gone into textures for all 4 kinds of crates. With the least possible polygons, the detailed textures make them look realistic with just one map (diffuse).