The price difference will down to a number of differing factors.
In the UK, Schumacher distribute Nosram and SMD distribute LRP.
Schumacher should be able to buy in bigger volumes, getting a better deal, but they're also a bigger company, with higher running costs.
I don't know enough about SMD to comment properly, but they are bringing in a lot of LRP stuff that we never had when it was Helger / Horizon, and have felt the pressure of the exchange rate.
At the end of the day, you either like red or blue, but you get what you pay for at the end of the day, I mean, I'm treating myself to a big TV next week, so my awkward decision is, do I go for the brand name at £X, or do I get the unknown brand for the same or cheaper. The brand name can charge extra as they're a brand name, but if the non-branded charges the same money, do you get more for the money, or just a rip-off.