According to the official website, the differences between a Standard and a General Purpose droplets are:
The most basic Droplet – a burstable portion of vCPU – along with a configurable amount of memory.
Simple or bursty applications such as low traffic web servers, blogs, discussion forums, CMS, small databases, dev/test servers, microservices, and repository hosting.
The most popular modern Droplet, with 100% dedicated vCPU, along with a balanced 4GB of memory for each vCPU.
Critical applications such as high-traffic web servers, e-commerce sites, medium-sized databases, and enterprise Software as a Service (SaaS).
Hope that this helps!