Reference:
A macro is a reusable search string that can contain any part of a search, such as search terms, commands, arguments, etc. A macro can have a flexible time range that can be specified when the macro is executed. A macro can also have arguments that can be passed to the macro when it is executed. A macro can be created by using the Settings menu or by editing the macros.conf file. A macro does not have to contain the full search, but only the part that needs to be reused. A macro does not have to have a fixed time range, but can use a relative or absolute time range modifier. A macro does not have to contain only a portion of the search, but can contain multiple parts of the search.

Explanation
https://docs.splunk.com/Documentation/Splunk/8.1.2/SearchReference/Chart

Reference:
The Field Extractor (FX) is a tool that helps you extract fields from your data using delimiters or regular expressions. Delimiters are characters or strings that separate fields in your data. The FX can detect some common delimiters automatically, such as pipes (|), spaces ( ), commas (,), semicolons (;), etc. The FX cannot detect tabs (\t) as delimiters automatically, but you can specify them manually in the FX interface.