Are these photopost tables ?
 

gal_admingroups
gal_admlog
gal_cache
gal_categories
gal_comments
gal_ecards
gal_exif
gal_extrafields
gal_favorites
gal_ipcache
gal_iponline
gal_laston
gal_notify
gal_photoextras
gal_photos
gal_photoviews
gal_settings
gal_sort
gal_sortmemb
gal_users
gb_cache
gb_media

everything with a gal_ prefix yes

what happen if i deleted these tables and can't restore them ? =s

the gallery has it is own db i created a new one for the gallery so why would it copy some tables to my forum db ? but would it harm my gallery if these tables are gone .... ? I did not realise any bug in my gallery when i deleted these tables.

You could have created or ran the install to your forum database. If your gallery database does not exist in the forum database and your gallery database is on its own you can delete photopost tables from your forum database sure.