Short answer: An unmanaged VPS gives you a fresh operating system and root access; updates, security, backups and troubleshooting are your job. A managed VPS adds the provider's administrators, who patch, monitor and support the server, usually with a control panel, for two to five times the price.
Managed vs unmanaged VPS explained
Unmanaged (self-managed) plans suit developers and anyone comfortable with Linux or Windows administration; they are the cheapest way to get a server.
Managed plans suit businesses without technical staff, agencies hosting client sites and anyone who wants cPanel or Plesk installed and maintained. Check exactly what 'managed' covers: some hosts manage only the operating system, others the web stack and applications too.
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Frequently asked questions
Do I need a managed VPS for WordPress?
Not if you can follow a setup guide or use a free panel such as CloudPanel or HestiaCP; choose managed if you do not want to handle updates and security yourself.