AWS is for scalable systems. If you aren't familiar with how to setup infrastructure, then you would be better off with DO.
While DO has the more traditional VPS server packages with space, bandwidth etc bundled together, AWS brought in the exact same matching service a few weeks ago called Amazon Lightsail.
AWS is basically a whole Datacenter at your disposal. Like what they say, with great power comes great responsibility and if you do not set them up correctly and ensure you don't have leakage, you might get a larger bill than expected. However, this isn't a surprise as the invoice is prorated and you can see your charge every single day and its a joke when people complain about this because unlike any other company you actually get you see your exact bill up to date day by day everyday and the predicted month end bill instead of getting a surprise at the end of the month.
DO has limitations when it comes to scaling as you are still stuck with the traditional VPS architecture and adding more disk, bandwidth or upgrading systems is not as easy as on AWS.
DO can get expensive for larger networks because you end up paying for a fixed/bundled resource than pay per use.
In AWS you are billed for each item on a hourly pro-rata basis everyday, no monthly minimum charges nonsense. So if you add 30GB and use it only for 2 days, you are charged only for those 2 days for the 30GB, essentially you pay the price of 2 GB per month.
As mentioned before, AWS is a Datacenter at your disposal and the amount of services and tools available for you to monitor, firewall, logging, templating etc is unmatched by DO.
