Winzip creates archives only in zip format. 7zip creates archives in zip, 7zip (7z), bzip2 (bz2), and a few other formats. 7zip format generally compresses better than Winzip in their native formats, but is not as fast. Both are based on LZ77, which compresses by replacing string matches with pointers to earlier occurrences. The zip format uses deflate, which encodes matches using Huffman codes. 7zip uses LZMA, which uses context models and arithmetic coding to encode matches and literals. Context modeling is slower but compresses better. Moreover, 7zip supporting much more compression formats.