Is Bottle gourd and white pumpkin same?
From the picture and your description "Inside It was like cucmber. Some seeds and soften stuffs", I would say that it is most likely a zucchini. Zucchini come in white (which is actually a pale green), green (which is pine green) and yellow, and the inside looks cucumber-like, although it is not as pleasant to bite into while raw. A further clue would be the hardness of the rind - zucchini slices as easily as a cucumber, while other related plants (including gourds) have a rather hard outer rind which requires some pressure to split. 

If it is not a zucchini, there is probably no better way to classify it. There are tons of cucurbitas and hybrids between them, and cooks don't have precise names for all, only for the most commonly eatem ones. So "pumpkin" might be the best you are left with. You can of course also say "white pumpkin" if this is the preferred name regionally, but don't be surprised if you ask somebody from a different region for a "white pumpkin" and you get either a puzzled look or a random pumpkin-related plant with whitish skin.