General:
* Autumn: In Britain, it's the season between summer and winter. In America, it's called "fall."
* Biscuits: In Britain, biscuits are what Americans call "cookies." In America, biscuits are a fluffy, savory bread.
* Chips: In Britain, chips are what Americans call "fries." In America, chips are what Brits call "crisps."
* Crisps: In Britain, crisps are thin, fried potato snacks. In America, crisps are what Brits call "chips."
* Dungarees: In Britain, dungarees are what Americans call "overalls." In America, dungarees are a type of denim trousers.
* Fanny: In Britain, this is a slang term for "vagina." In America, it refers to the buttocks.
* Flat: In Britain, a flat is an apartment. In America, it's an apartment that is also on the ground floor.
* Hoover: In Britain, this is a brand name for a vacuum cleaner, but it's often used as a verb to mean "to vacuum." In America, it's just a brand name.
* Holiday: In Britain, a holiday is a vacation. In America, a holiday is a public festival.
* Nappy: In Britain, this is a diaper. In America, it's a type of fabric.
* Pavement: In Britain, the pavement is the sidewalk. In America, it's the road surface.
* Petrol: In Britain, this is gasoline. In America, it's called "gas" or "gasoline."
* Rubber: In Britain, rubber can mean both the material and a condom. In America, it's usually just the material.
* Shop: In Britain, a shop is a store. In America, a shop is a specific kind of store, usually a small one.
* Sweet: In Britain, a sweet is a candy. In America, it's a general term for something that tastes sugary.
* Torch: In Britain, a torch is a flashlight. In America, it can also refer to a burning flame.
* Toilet: In Britain, this is a bathroom. In America, it's just the plumbing fixture.
* Trainers: In Britain, trainers are athletic shoes. In America, they're called "sneakers."
* Trousers: In Britain, trousers are pants. In America, they're called "pants."
Food and Drinks:
* Scones: In Britain, scones are usually served with jam and cream. In America, they are often more dense and are not usually served with cream.
* Tea: In Britain, tea is usually black tea brewed with milk. In America, tea is more often iced tea, herbal tea, or green tea.
* Pudding: In Britain, pudding is a dessert. In America, it's a savory dish made with bread or meat.
Other:
* Boot: In Britain, a boot is the trunk of a car. In America, it's a shoe.
* Bum: In Britain, this is a slang term for "buttocks." In America, it's a homeless person.
* Cheeky: In Britain, cheeky can mean "bold" or "impudent." In America, it's not as common and often means "rude."
* Gaffer: In Britain, this is a slang term for "boss" or "foreman." In America, it's not used.
* Mucky: In Britain, mucky means "dirty." In America, it's not as common and often means "gross."
* Rubbish: In Britain, rubbish is garbage. In America, it's often called "trash."
This is not an exhaustive list, but it gives you a good starting point. It's important to remember that these differences in meaning can vary depending on the region and the context.