I use Sitecore, but as an end user, not a developer.
Sitecore themselves have videos and trainings. They try to rope you into paid trainings, but there are a lot of resources online. Honestly, though, that's not the way I typically learn. I poke around and turn to Google when I get stuck. So I mostly haven't had the patience to go through their documents.
That said, if you can find a 10-minute video that gives you a quick tour of the suite, that might be helpful.
What's the difference? Well, what's the difference between an automotive engineer and a driver?
For the end user, Sitecore is a mouse and click, WYSIWYG environment. For the developer, Sitecore is an ASP.net content management and user experience framework.
If you're familiar with Wordpress, I would call the end user the person who writes content. Some people might say the site visitor is the Wordpress end user, but that person doesn't "use" Wordpress, they "use" the website WP generates.
I would call the developer the person who creates custom plugins and themes.
Somewhere in between is the person who installs plugins and configures the site (what in Drupal parlance would be a "site builder" rather than a user or a developer).
Sitecore is quite different, but not that complicated. I have found many parts to be buggy, but it's mostly fairly simple once you have the basics. The basics are a bit complicated as there are multiple ways to edit a page and it can be hard to find the pieces.
If you get lost, use the Experience Editor (rather than the Content Editor) and choose "Edit related item." It will open that item in a new frame and you can then look at the info at the top and figure out where the underlying component is. Thought I expect that if you haven't seen Sitecore yet, that was all just jibberish.
Sitecore is proprietary and they are as interested in protecting their providers as they are in providing for users. So their website, unlike Wordpress or Drupal, provides almost no free training worth anything. They are mostly focused on getting you to attend expensive training events.
Have been using Sitecore for a couple of days and am getting stuck on something. I have googled but found nothing that made any sense. One website has to change all of it's links on all of it's pages, from something/UK/home/something to something/Japan/home/something - without going through all 300 pages, with on average 15-20 links on each page, how do you do a find and replace please? Preferably using a wildcard.
Pretty sure you're going to have to have a developer dump the database, do the full search and replace, upload the database.
I don't think there's any way you can do this from within Sitecore and natively, you can't do it with any system I know, but there are methods for others. I recently did this for a Wordpress site. The challenge on Wordpress or Drupal is that you have serialized data, so you can't just do a search and replace. you need to run a script.
I know nothing about ASP.net or what database you're using, so I can't say what you would need to do in this case.