When we were in Crete this summer , eating out was far cheaper than Spain, and excellent quality too. Many people speak English in Greece because Greek is difficult to learn apart from social greetings maybe.
Corfu is possibly like Majorca in that the latter has lots of rain!! Mainland Spain maybe drier, so too mainland Greece maybe drier.
Charlie is the best one to pass comment on comparisons.
I compared the price of buying food from supermarkets and cooking at home. There is no Carrefour in Corfu Island and prices in small stores is quite high.
An expresso was about 1.70 Euros which I found quite high.
A moussaka at various restaurants was about 7.50-9.50 Euros which is not very cheap.
A Fanta/Coke was about 1.7 – 2 Euros which again is not particularly cheap…
Maybe Crete is cheaper.
How are the beaches in Crete?