UK tea is stronger, US tea weaker, because most brands and types of US tea are generally intended to be drunk with nothing diluting it, such as milk, while the Brits -- aside from some individual's personal preference to have it "straight" -- usually put milk in it.
US tea is more what I would call an "herbal infusion", made to be tasted on it's own with only lemon, or honey, or something like that added. Brits don't traditionally drink their tea that way. British tea is almost an entirely different drink altogether, being traditionally the "strong black" kind meant for milk and sugar as it's partners although, as stated, some people don't always do that either.
When my ex (a Brit) came to visit me in the States, I bought him an American-produced pack of Tetleys thinking it would be the same as British Tetleys, and it STILL wasn't strong enough compared to the British Tetleys he was used to -- he had to use THREE bags of the weak US Tetleys, compared to the ONE bag he has here in the UK. Any American tea just isn't made with strength that possible milk-partnering would require of it in order to still taste good. They make it the right strength to be sipped "neat" but when a Brit wants milk in it, it turns to hell.
But yep, long story short, it's different.
