Fraud and theft are similar offences, both of which involve taking money, property, et cetera, that is not yours. And, in both cases, the accused needs to intend to take something that does not belong to them. The difference is that with fraud, the accused attempts to conceal their unlawful act with trickery or deceit. With theft charges, deceit or concealment of the unlawful act is not required.
Fraud charges also tend to be considered more serious.