Fundamental difference between t3 and t3a EC2 instances

Solution 1:

Per benchmarks at photographerstechsupport.com, t3 instances tend to be 10 to 20% faster than their equivalently spec'd t3a counterparts. I notice that the precision of some of the benchmark values is low enough (i.e. 0.06 vs 0.07, reported only to the nearest hundredth) that the actual difference could be anywhere between ~0 and 26%. However, based on multiple values it does seem the difference is about 15% overall.

This is reasonably close to the price difference of ~9%, making either choice a good option, depending on the compute performance need.

Solution 2:

t3a instances run on AMD EPYC CPUs, depending on your workload (threads, spikes, etc.), you will probably have similar performance if the right pieces match. In general, it seems that the t3 instances running Intel CPUs are usually faster.

You can also get a 10% discount on your EC2 computing bill:

Amazon Web Services (AWS) announces general availability of Amazon EC2 T3a instances. T3a instances are variants of T3 instances and feature AMD EPYC processors with an all core turbo clock speed of up to 2.5 GHz. T3a instances provide additional options for customers who are looking to achieve a 10% cost savings on their Amazon EC2 compute environment for applications with moderate CPU usage that may experience temporary spikes in use.

Reference: https://aws.amazon.com/about-aws/whats-new/2019/04/amazon-ec2-t3a-instances-are-now-generally-available/?nc1=h_ls