To explain a little more, a crib is a bed that is usually elevated on long legs (to make it easier for adults to put the child in and take it out) that has bars (or sometimes netting) on the sides so that the child cannot fall or climb out. Here is a picture of one.
A cradle is usually lower is shaped like a basket. An essential feature of a cradle is that it can be rocked from side to side. If it doesn't rock, it isn't a cradle. Here is a picture of one that is fairly traditional. There are more modern designs, as well.
There is an AE/BE point to be made here - see cot.
The AE crib is a BE cot.
A BE cot is a rectangular bed with bars - suitable for kids up to ~3 if you're lucky.
A BE crib is more or less equivalent to a BE cradle.
Well, if we're going on about cots, I guess someone should add that a cot in AE is a small, low bed, often one that can be folded up for storage. This is an example of a camping cot and this is a folding guest cot.