There are some basic difference in between Custom tag and Coldfusion Component in which some are as follows:

• Custom tags have no formalized parameter passing and validation mechanism; CFCs (Coldfusion Component) do.

• Custom tags have a single entry point; CFCs can have multiple entry points. This makes it possible to create a single component that does many related actions.

• Custom tags are designed to contain code; CFCs are designed to contain both code and data.

• Custom tags are accessible only by Coldfusion and only locally; CFCs can be accessed as web services, opening up a whole new world of reuse possibilities.