Saying “I realized X” seems different from saying “I actualized X.” Actually, saying the latter seems odd to me. “Actualizing” something seems to belong to engineering or similar roles (relatively odd to me, though I’m around implementors daily). “Realizing” something is common. One actualizes a project. To realize this seems to be like saying: I appreciate this.
But someone might see no difference between calling something “real” and calling it “actual,” while readily seeing a difference between realizing and actualizing.