The Keyword Analyzer does not perform any analysis on the input text. It creates a single token representing the entire input. This is useful for fields where you only want exact matches. For example, a field containing keywords or tags that may contain spaces that another analyzer might interpret as token boundaries.
The simple analyzer performs only minimal analysis on the input.
The Standard Analyzer is like the Simple Analyzer but also adds English stop word removal.
The Detect Language Analyzer is used to examine input text, use heuristics to determine a best guess at the language, and index the ISO 639 Language Code.