They both have:
1.) Wonderful artwork-
2.)A slight similarity-
3.) good romance-
4.) a very dramatic scene like this clannad-
5.) Otome looks so youthful, beautiful, and cute like Nagisa!!!-
it gets very dramatic at the last few episodes.
the relationship between the protagonist is the same [ultra spoiler theree] :<
but it's too hard to explain w/o spoiling >w<
anwaiz, AKANE is more harem/ecchi, whilst DA CAPO II SS is more romance/mystery-ish
similar relationship, again!
explaining more would give spoilers :<
both aren't ecchi/harem much and have a decent amount of romance in it :33 and to those who watched Canvas, DA CAPO II SECOND SEASON is more SADDER at the end :P
They're both harems with a touch of supernatural and the main characters are just lovable assholes. The greatest similarity between them are the opening scenes, where "a certain character" talks about their dreams. If you liked Da Capo II Second Season, I would totally recommend Kanon 2006 since it is basically better in every way. (Ex: character development, animation style, story telling, etc)