Esperanto: Mi staras ekster la domo. = angla: I stand OUTSIDE the house (Preposition)
Esperanto: Mi promenas ekstere. = angla: I am walking OUTSIDE (Adverb: I am on the outside, not inside, walking about)
Esperanto: Mi promenas eskteren. = angla: I am walking OUT. (Directional: I am beginning my walk inside; I am walking, and at the end of my walking I will be outside)