Is it possible to migrate content from "Glossary" extension to SEO Glossary?

Not in an automatic way, but there is a tutorial make by a customer on our forum (thanks to corpus).

Use these carefully and always keep backups

1. Open phpmyadmin
2. go to jos_glossary table and click on the SQL tab
3. paste this in the sql query

SELECT `id`,`published`,`checked_out`,`tdate`,`tterm`,`tfirst`,

`tdefinition`,`tname`,`tmail`,`tcomment`,`tedit`,`catid` FROM `jos_glossary` WHERE 1

4. Press the Go button, you can see now the results.
5. scroll down to the Query results operations and click in the Export link
6. in the new window in the Export type choose INSERT and uncheck the Structure option. Press the Go button and download the sql file
7. Open the downloaded sql file with a good text editor (Notepad++, gedit, komodo)
find the lines

INSERT INTO `jos_glossary` (`id`, `published`, `checked_out`, `tdate`,

 `tterm`, `tfirst`,`tdefinition`,`tname`, `tmail`, `tcomment`, 

`tedit`, `catid`) VALUES

PROBABLY IT WILL BE MORE THAN 1 TIME in the sql file
and make them like this

INSERT INTO `j25_seoglossary` (`id`, `state`, `checked_out`, `checked_out_time`,

`tterm`, `tfirst`, `tdefinition`, `tname`, `tmail`,`tcomment`, 

`tedit`, `catid`) VALUES

8. Save the sql file and go back to phpmyadmin and import it

Please first of all make backups. Second pay attention in the prefix (mine was jos_ and j25_)