The difference is how they are mechanically keyed. Keyed hash is a step towards encryption. Encryption can be keyed from a passphrase or a PKI certificate. Though tries can be keyed by character strings, they need not be. A cluster can be keyed with a B-Tree index or a hash table. Each version is keyed to a specific language. The paper is normally keyed to a frame around the woodblocks. Only one answer can be keyed as correct. Each tablet is keyed to a specific degree in the Temple hierarchy. Some early CW transmitters employed an arc converter that could not be conveniently keyed. A derivative of the F alto horn, it is keyed in F. The developers are currently working on adding keyed hash like HMAC (SHA256). The grid is keyed to his unique brainwaves. The highest varieties are not normally keyed. Many packages are keyed to ensure the proper insertion of the CPU.