A caddie is (1) an attendant to a golfer, or (2) a device used for holding or carrying a collection of items. A caddy is a small container used for holding tea. Caddy, like the tea-holder it refers to, is primarily British.
Though caddie and caddy are separate words with distinct origins (caddie from the French cadet, and caddy from the Malay kati), there are two reasons why confusing them is not a serious error. First, many dictionaries accept caddy as a variant spelling of caddie, and in current news publications the word for a golfer’s assistant is spelled caddy about a quarter of the time. Second, a caddy is a type of caddie (in the second sense).
Throughout the English-speaking world, caddie denotes a golfer’s attendant—for example:
Notably, Tiger Woods is in match against Adam Scott and former caddie Steve Williams for the second time in the event. [New York Times]
This is not to say that the caddie’s role is not that important. [Irish Times]
Watson travels only with his caddie, a physical trainer, and his wife. [Sydney Morning Herald]
Caddy is an accepted but less common spelling for the golfer’s helper. It also appears throughout the English-speaking world—for example:
If they were, former Presidents Dukakis and Gore would be out playing golf together and boring their caddy to tears. [The Caucus blog at New York Times]
[H]is recent comments about Tiger Woods don’t really stand up to the reality of how the gobby caddy had the golfer as his best man when getting married. [Irish Times]
‘That’s way different,” Kim’s caddy muttered. [Sydney Morning Herald]
Tea containers are rarely newsworthy, so caddy in its original sense is hard to find in news publications.