Actually it is the same thing and possibly worse if you do not have a written agreement to go along with it. Consider what would happen if they need the funds they gave you to pay for e.g. a medical emergency, or to keep their house from going into foreclosure in case they lose their job, or some other reason and what if you do not have that extra money to repay them right then. And what if it is your wife's family you borrowed from, now you force your wife to choose "sides", what will that do to your relationship? Just saying!
The mower was a 22" Jacobson greensmower, I was using it at no additional charge to pay him (the customer) back so it would be mine. From what I heard, the guy I sold to, broke it, used a regular push mower for a while and then told the customer it was too much work and started using a 48inch walk behind. Though I did not technically sell it to him, neither did he technically buy it, yet he kept it and even tried to sell it.