I have been asked what the difference was between a squire and an esquire in the Middle Ages
The short answer is that they were just two different ways of spelling the same word, derived from the Old French escuier, esquier, eskuwier, or eschuier. A squire was either a superior servant, below a knight and above a yeoman or valet, or a person of the social rank from which such men were recruited, typically a country gentleman with less land than a knight. By the 14th century, some wealthy squires had as much land as a knight,and squires in the first sense could come from the families of respectable merchants: Geoffrey Chaucer, who served as a royal squire, was a vintner's son.
By this time a squire in service might be a domestic servant, but might also serve as a military commander or, like Chaucer, a bureaucrat.
The words didn't diverge in meaning until the 17th century or later, when esquire in England became a polite suffix for any person that might be considered a gentleman,including a lawyer, but squire tended to refer to substantial country gentlemen.