Below is a table that briefly goes over the similarities and differences between Dynamic Fields and Lookup Fields.
|Dynamic Fields||Lookup Fields|
|Stays linked to the original entry*||Yes||No|
|Retains its value, regardless of changes to the original entry||No||Yes|
|Quickly and easily create cascading fields||Takes time||Yes|
|Populate post categories||Yes||No|
|Populate other fields with values from a selected entry **||Yes||Yes|
|Populate other fields by searching entered values||No||Yes|
|Dynamically display information from the selected entry||Yes||Yes|
|Display any value from the linked entry in an email or View||Yes||No|
|Automatically removes duplicate options||No||Yes|
* Dynamic fields store an entry ID. When changes are made to the original entry, the submitted value of the Dynamic Field is updated/deleted to match the original entry. Lookup fields store the value from the field that they're pulling data from. The submitted value of the Lookup Field remains separate from the original entry and retains its value.
** Dynamic fields can populate a field with values from a selected entry if the Dynamic field is in a separate form; learn how here. Lookup fields can dynamically populate certain fields with values from a selected entry. This is currently supported for the fields listed here.