Probably the AWS m4 instance type, meant for general purpose workloads (and replaced with the m5 instance type about a year ago).

https://aws.amazon.com/ec2/instance-types/m5/

AWS instance type.

"M4 instances provide a balance of compute, memory, and network resources, and it is a good choice for many applications."

https://aws.amazon.com/ec2/instance-types/

GP probably references an AWS EC2 machine type: https://aws.amazon.com/fr/ec2/instance-types/

I guess they're taking about the AWS EC2 instance type

https://aws.amazon.com/ec2/instance-types/

Its the bigger brother of m3.

AWS ec2 instance type