Shared nodes can be used by a group of customers, so basically anyone who chooses a free plan of 40k requests or any other request package, in fact, uses shared nodes. Shared node is an entry-level solution of our toolkit: in this mode, a GetBlock user shares nodes infrastructure with his peers;
To start using shared nodes, please, register an account and get an API key. 

https://getblock.io/nodes/

A dedicated node is a node that can be yours exclusively, it is build individually built on request and can be customized 
Dedicated nodes hosted by GetBlock is a premium solution: it allows our clients to leverage the entire node solely for their blockchain-based projects; GetBlock provides a private server to the required blockchain for those who need a maximum speed without any rate limits.

https://getblock.io/dedicated-nodes/

So if you want to work with a Blockchain node and launch a crypto project, but there’s not enough space on your computer or the documentation is quite complicated to understand, or maybe you want to concentrate on the product development and not spend resources on node management, GetBlock is a solution that will help! https://getblock.io/