I have several workloads that just invoke Lambda in parallel. Now I effectively have a 1000 core machine and can blast through large workloads without even thinking about it. I have no VM to maintain or OS image to consider or worry about.
Which highlights the other difference that you failed to mention. Hertzner charges a "one time setup" fee to create that VM. That puts a lot of back pressure on infrastructure decisions and removes any scalability you could otherwise enjoy in the cloud.
If you want to just rent a server then Hertzner is great. If you actually want to run "in the cloud" then Hertzner is a non-starter.