Which is better for webhosting, Linux or Windows ?
If we're talking bang up to date hosts (tech wise), then realistically both will offer stable hosting with no clear choice, but......
and what is the difference between the two ?
If you want to use ASP, Access database or VBScript, then Windows hosting is what you'll need. If not, then you're better off going with Linux hosting because in general its cheaper.
What are the most reliable webhosts in the UK & US
I use www.dataflame.co.uk - they're not the cheapest, but they're very reliable and they have 24/7 online help, so if you need a bit of tech help someone is always at hand to chat to. I've been with them for years and won't be swithcing anytime soon.