Scammers have a wide range of tricks that they employ to try and part unsuspecting internet users from their hard-earned cash and/or personal details.
Scareware and Ransomware are quite different things (one is certainly more serious than the other), but would you be able to spot the difference and, more importantly, protect yourself from both?
The main difference is this - if you encounter Scareware, you are probably still safe (just) from being scammed; you should close your browser (immediately!), disconnect from the internet and run a full scan using up-to-date anti-virus software. If you encounter Ransonware, on the other hand, you may have to restore your PC to avoid paying a fee to scammers to unlock your files or regain access to your computer.
Scareware mainly consists of browser or Windows-style popups, like those discussed in this article, which can appear when you visit a compromised website or after downloading a malware-infected attachment from a dodgy email. It tries to scare you into clicking links in the popups that will download a virus or other malware onto your machine; this can enable a scammer to steal your data. They can be very convincing - an example is in the attached image.
If Scareware appears when you're browsing a website, it most likely means that the website has been hacked or is dodgy. Close your browser immediately and run a full anti-virus scan (always make sure your anti-virus software is up-to-date). Don't revisit that website.
If the Scareware appears when you're not browsing the internet, it means your computer is infected. The Scareware could still compromise your data, so run a full system scan with your anti-virus software.
Ransomware comes in several varieties, of varying degrees of seriousness. It may lock your computer, making it unusable (examples of this type include Kovter ransomware), or it could encrypt your personal data and demand that you pay a fee in bitcoins to recover it (examples of this type include CryptoLocker ransomware).
Although Ransomware is very serious, you may be able to recover your files without paying the scammers a penny. Try restoring your computer using the System Restore function in Safe Mode, or by using a Windows Repair DISC.
We suggest reading this article on PC World which explains how to do this.
Above all, stay safe - keep away from dodgy websites, don't download files from torrent sites and never open attachments in suspicious emails.