What are the check tables and value tables?

Check Table:
The ABAP Dictionary allows you to define relationships between tables using foreign keys . A dependent table is called a foreign key table, and the referenced table is called the check table. Each key field of the check table corresponds to a field in the foreign key table. These fields are called foreign key fields. One of the foreign key fields is designated as the check field for checking the validity of values. The key fields of the check table can serve as input help for the check field.

Value Table:
Prior to Release 4.0, it was possible to use the value table of a domain to provide input help. This is no longer possible, primarily because unexpected results could occur if the value table had more than one key field. It was not possible to restrict the other key fields, which meant that the environment of the field was not considered, as is normal with check tables.

In cases where this kind of value help was appropriate, you can reconstruct it by creating a search help for the data elements that use the domain in question, and using the value table as the selection method.

Check table will be at field level checking.

Value table will be at domain level checking