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##### SUMMARY
<!--- Explain the problem briefly below -->
Ansible currently contains two modules for managing AWS EC2 instances: [`ec2`](https://docs.ansible.com/ansible/latest/modules/ec2_module.html) and [`ec2_instance`](https://docs.ansible.com/ansible/latest/modules/ec2_instance_module.html).

There is considerable overlap between the modules, but it's unclear what the differences are and why there are two modules in the first place.

##### ISSUE TYPE
- Documentation Report

##### COMPONENT NAME
<!--- Write the short name of the module, plugin, task or feature below, use your best guess if unsure -->
ec2
ec2_instance

##### ANSIBLE VERSION
<!--- Paste verbatim output from "ansible --version" between quotes -->
```paste below
ansible 2.10.0.dev0
  config file = /home/user/.ansible.cfg
  configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /home/user/ansible/lib/ansible
  executable location = /home/user/ansible/bin/ansible
  python version = 3.7.5 (default, Oct 27 2019, 15:43:29) [GCC 9.2.1 20191022]
```

##### CONFIGURATION
<!--- Paste verbatim output from "ansible-config dump --only-changed" between quotes -->
```paste below
RETRY_FILES_ENABLED(/home/user/.ansible.cfg) = False
```

##### OS / ENVIRONMENT
<!--- Provide all relevant information below, e.g. target OS versions, network device firmware, etc. -->
Debian bullseye/sid

##### STEPS TO REPRODUCE
<!--- Describe exactly how to reproduce the problem, using a minimal test-case -->

<!--- Paste example playbooks or commands between quotes below -->
```yaml
N/A
```

<!--- HINT: You can paste gist.github.com links for larger files -->

##### EXPECTED RESULTS
<!--- Describe what you expected to happen when running the steps above -->
N/A

##### ACTUAL RESULTS
<!--- Describe what actually happened. If possible run with extra verbosity (-vvvv) -->

<!--- Paste verbatim command output between quotes -->
```paste below
N/A
```

user_data:
    version_added: "0.9"
    description:
      - Opaque blob of data which is made available to the EC2 instance.
    type: str
  instance_tags:
    version_added: "1.0"
    description:
      - A hash/dictionary of tags to add to the new instance or for starting/stopping instance by tag; '{"key":"value"}' and '{"key":"value","key":"value"}'.
    type: dict
  placement_group:
    version_added: "1.3"
    description:
      - Placement group for the instance when using EC2 Clustered Compute.
    type: str
  vpc_subnet_id:
    version_added: "1.1"
    description:
      - the subnet ID in which to launch the instance (VPC).
    type: str
  assign_public_ip:
    version_added: "1.5"
    description:
      - When provisioning within vpc, assign a public IP address. Boto library must be 2.13.0+.
    type: bool
  private_ip:
    version_added: "1.2"
    description:
      - The private ip address to assign the instance (from the vpc subnet).
    type: str