Scales are always different. You can weigh yourself 1 minute at home, and go straight to the gym, and 10 mins later and weigh yourself again and be totally different. Different scales weigh you different. At home scales are cheaper and therefore arent as acurate as an expensive scale maybe at the gym. Also, what clothing your wearing, or if you've had anything to eat or drink can affect sudden weight changes! I hope this helped atleast a bit :) Good Luck!