The technical differences are customer and data center support. How long has the free web host been online? Do they change domain names every other month? Reseller Free Web Host, Dedicated Server Free Web Host? The History of the free or paid web host. So many things to consider before diving rite in.
Free web host providers with a reseller means the end user (free account holder) does not have to worry about all the technical stuff. Only the reseller has to. The end user just uploads, manages and advertises their website and content. But if you need specific ports opened for like a "gaming statistics" plug in (as an example) you have to contact your web space provider, make a request, and wait for them to get with the data center to first ensure that port can even be opened. This is then specific for that account on the reseller. Then the web space provider gets back to the account holder. So there is some "middle man" work to be done.
Free web host providers running dedicated boxes means they better know what they are doing. Your web space provider has to know commands on the fly and how to secure them. Like iptables -I INPUT -p tcp/udp .......... service iptables save - for a specific account. Again this is only using a gaming port to be opened, as an example. Free web hosts using a dedicated server for free web hosting services, means you deal directly with the person Leasing the box on a rack, or if they are colo and paying for their own 1,2,3,4,5 u rack space.
Paid hosting, using the same scenario, means the end user calls the data center ( then told to open a ticket lol ) and handles the request one on one.
Service uptime between paid hosting and free hosting has some differences. The biggest one is a free web host provider that over sells. That means the provider crams the dedicated server to the max with accounts on the usable disk space, and PRAYS OUT LOUD :fangel: all those accounts do not use full resources. This usually causes the web host provider service to lag, time out and in some cases get shut down because the data center will not put up with it, based on their TOS.
Do you want a shared IP, dedicated IP, more control over your free account, full cPanel service rather then a chopped down version which forces you to upgrade, ads on your pages for the free space, some do not place ads, forced ads you have to click or the most annoying is post to host or take a survey every day which usually doesn't work right anyway because of poor scripting.
Do some shopping around and research.
Shaun