Difference between Go to bed in one’s boots and Go to bed with one’s boots on

go to bed in one’s boots—(dated sl.) be very drunk:

• If old Jones drinks much more, he’ll go to bed in his boots.

go to bed with one’s boots on—(sl., of men) use a contraceptive:

• You can’t make them wear something. I tried to tell Reggie once…. “No fear,” he said, “I don’t go to bed with my boots on!”