Is it safe to say that , in terms of availability EMR serverless would be a better option than EMR ?

Hello,

Considering low-latency, high-throughput, and highly redundant networking, EMR-S also deploys the workers in a given subnet at any given situation. Amazon resources are created in a subnet which is a subset of available IP addresses in an Amazon VPC. For example, a VPC with a /16 netmask has up to 65,536 available IP addresses which can be broken into multiple smaller networks using subnet masks. As an example, you can split this range into two subnets with each using /17 mask and 32,768 available IP addresses. A subnet resides within an Availability Zone and cannot span across zones. As a whole, the AWS global infrastructure is built around AWS Regions and Availability Zones. AWS Regions provide multiple physically separated and isolated Availability Zones, which are connected with low-latency, high-throughput, and highly redundant networking. Please refer this doc for more information[1].