Difference between AWS EC2 T4g and T3a instance types?

I saw that T4g and T3a instances from AWS EC2 are really similar, and they are roughly the same price. Is there any notable difference in performance? I noticed that the T4g uses an ARM-based processor while the T3a uses the AMD EPYC processor, but I don't know how that affects performance.

I am just hosting a basic LAMP stack for my projects, with little to no traffic.

We cannot possibly know how these will perform for your workload. Rent both and test. Optimize according to your requirements: cost, performance, whatever.

Despite the high level similarities, these are different CPUs. Instruction sets, compiler optimizations, cache configuration, NUMA, fab processes, thermals and boost clocks, all different. Whether these add up to a significant difference for you, that is what testing is for. But certainly the price and performance dimensions will be at least a little different.