"아직" with "도(also, even, too)" carrys more weight than "아직" meaning it conveys a stronger sense of "아직" and often used in an emotional sense. For example, He is still sleeping. 1) 그는 아직 자고 있다 (just a statement) 2) 그는 아직도 자고 있다 (It's already 11am, but he's still sleeping. You might be upset or complaining about his oversleeping) It's still raining 1) 비가 아직 오고있다 (just a statement) 2) 비가 아직도 오고있다 (You might be sick and tired of raining or you may be worried about raining) \^o^/

1. 아직 1) Yet , still ex) 아직 해결되지 않다. ---> It is yet to be sloved. 아직 비가내린다.---> It is still raining. 2) more; besides ex) 아직 더 있다 ---> I have still more. 아직 더 가야 된다--->We have more miles to go. 3) only ex) 아직 조금 밖에 안 되었다.---> It is only a little since we started. 2. 아직도 : yet,still 1) 내 실력은 아직도 부족하다. ---> My ability is still far from perfect. 결론: 두 단어는 같은 뜻입니다. 바꾸어서 써도 같은 의미가 됩니다. The meaning of both words are the same.