England and America are two countries which are divided by a common language that is "English". The cookie that is eaten in the United States seems to be the biscuit in the U.K., both biscuits and cookies are often confused due to some of the similar qualities in them.
In the UK, your biscuit might be topped with chocolate or have currants in it. You might dip it in your cup of tea, or have one (or two or maybe three) as a snack after lunch. If you were in the US, you might put bacon and eggs on it or smother it in gravy and have it for breakfast. Or you might put a piece of chicken on it and have it for dinner.
A cookie is a soft, squishy, moist biscuit in the U.K., British cookies tend to be bigger and more substantial than a British biscuit. In the US, a cookie covers both what the British would call a biscuit and a cookie.