Using some online calculators, the overall tax rate on $500k / £360k actually works out to be exactly the same. But that is before property taxes in the US, although not counting any exemptions (more difficult to compare pensions allowances that you would pay out of gross salary etc.). Also not counting total cost to employer, which could well be higher in the UK.

But seems like overall it would work out to be about the same. Certainly not a huge difference in tax levels.