Crème anglaise is what you or I would call "Custard".
To the rest of the world "Custard" is a generic term for loads of different things, any kind of liquid made of eggs and milk basically. Crème anglaise is the specific kind of custard that Brits think of, but that's just us - hence the name "English Cream". Don't ever ask for "custard" with your strudel in Vienna, it's vanilla sauce (aka custard).
Chefs like to call it crème anglaise even in the UK 'cause it sounds more foody. Also distinguishes between 'proper' custard made from eggs, cream, milk, sugar and vanilla and the stuff in a packet.
HTH