An instance represents one running copy of an Amazon Machine Image (AMI). All instances based on the same AMI start out identical. The Instance type defines the memory, CPU, storage capacity, and hourly cost for an instance. Some instance types are designed for standard applications, whereas others are designed for CPU-intensive, memory-intensive applications, etc. Documentation: http://docs.amazonwebservices.com/
(Amazon Machine Images) AMIs are like a template of a computer's root drive. They contain the operating system and can also include software and layers of your application, such as database servers, middleware, web servers, etc.
A fixed (static) IP address that you have allocated in Amazon EC2 or Amazon Virtual Private Cloud and then attached (or routed) to your instances. Elastic IP addresses are associated with your account, not specific instances. They are elastic because you can easily allocate, attach, detach, and free the addresses as your needs change. Unlike traditional static IP addresses, elastic IP addresses allow you to mask instance or Availability Zone failures by rapidly remapping your public IP addresses to any instance in your account.
A feature of the load balancer that binds a user's session to a specific application instance so that all requests coming from the user during the session are sent to the same application instance. By contrast, a load balancer defaults to route each request independently to the application instance with the smallest load.
All virtual servers created using the system are grouped into Environments. Environments can be created either on the fly or using an existing Template.
Templates are a way of pre-defining an environment with set characteristics that you may want to use later or multiple times in the future. This could include the number and type of virtual servers to create and what data should be attached to those servers when the environment is created.