The definitions are the same, i.e., paid and free versions use the same definitions.
But you can’t copy one folder over the other.
To analyze your system, please, upload (attach) the avast log:
C:\ProgramData\AVAST Software\Avast\log\Setup.log
or C:\Program Files\Alwil Software\Avast5\Setup\setup.log
If the file is too big for the forum, post the last 400-500 lines of it.