The key distinguishing factor between direct and collateral appeals is that the former occurs in state courts, and the latter in federal courts.
ðə kˈiː dɪstˈɪŋɡwɪʃɪŋ fˈæktɚ bᵻtwˌiːn dᵻɹˈɛkt ænd kəlˈæɾɚɹəl ɐpˈiːlz ɪz ðætðə fˈɔːɹmɚɹ əkˈɜːz ɪn stˈeɪt kˈoːɹts, ænd ðə lˈæɾɚɹ ɪn fˈɛdɚɹəl kˈoːɹts.