Sinndho's given you the links to the definitions.
From a practical standpoint, in Access VBA, Text is seldom used, the rare exception being in code in the OnChange event of a Textbox, to determine how many characters have been entered, when this is needed, such as when alerting the user to how many characters are left for use. As you already know, it require that Focus currently be on the Textbox.
The Value Property is used for basically everything else, from reading the data currently in the Control's underlying Field to assigning data to the same.
Since the Value Property is the Default Property for Textboxes, in code it can be omitted. So
Me.TextboxName.Value
can simply be written as
Me.TextboxName
Linq ;0)>