Are all scales the same?

This morning, I had planned on weighing myself before I left for work.  Of course, I forgot to.  We just so happen to have a scale at work.  What does a law office need with a scale? The other women and I were weighing ourselves every Thursday and trying to lose weight, but I stopped when I kept gaining.
The other night, I stepped on the scale at home and it read 310.1. Oh... my...God.  Are you serious? Do I need to get my eyes checked? Does it really say that?  I wanted to go sit in the corner and cry. That is officially my heaviest weight EVER! I feel sick just thinking about it.
This morning when I got on the scale at work, it said 304.4. That could be an improvement, or it could just be that the scales are different, which is the greatest possibility.  I will be getting on the scale at home tonight just to check. Hopefully the one at home will read even less. I said hopefully. I can still hope.
On positive notes, I did drink the recommended 64 oz. of water yesterday.
Funny story: Last night, I was almost finished with my bottle of water. I showed D how much I had left and stated that I was almost finished with my recommended daily intake.  He looked over at me and said "I finished my daily intake by 9:00 this morning." I just looked at him then asked "You drank to big bottles like this by 9:00..... this morning....?" He responded, "No. I drank a 20 ounce bottle of water."
I proceeded to tell him that eight glasses of water was the recommended amount.  Of course, he didn't believe me though. But hey, at least he was drinking some water because that is rare for him. Usually he has an IV of Pepsi running into his arm.  Oh how I love him and his quirks.