The house position of most planets will not vary from one house system to another, but sometimes if a planet is close to the border of a house it can change house positions from one house system to the next.
This free astrology birth chart program uses the Placidus method of calculating astrological houses which is the most popular world wide. Many American astrologers prefer the Koch house system, and there are at least 30 other systems. The house position of most planets will not vary from one house system to another, but sometimes if a planet is close to the border of a house it can change house positions from one house system to the next. In cases like this, it might be helpful to think of that planet as being 'cuspal' as far as the house is concerned and it may be that both different house interpretations have some meaning for you. That particular planet in question may also help you determine which house system works best for you personally. On the other hand, when there is a doubt, some astrologers will 'promote' that planet to the higher numbered of the two houses in question.