xzcmp and xzdiff invoke cmp(1) or diff(1) on files compressed with xz(1), lzma(1), gzip(1), bzip2(1), or lzop(1). All options specified are passed directly to cmp(1) or diff(1). If only one file is specified, then the files compared are file1 (which must have a suffix of a supported compression format) and file1 from which the compression format suffix has been stripped. If two files are specified, then they are uncompressed if necessary and fed to cmp(1) or diff(1). The exit status from cmp(1) or diff(1) is preserved.
The names lzcmp and lzdiff are provided for backward compatibility with LZMA Utils.