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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
```

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##### 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
```

if terminated_instances:
                    module.fail_json(msg="Instances with id(s) %s " % terminated_instances +
                                     "were created previously but have since been terminated - " +
                                     "use a (possibly different) 'instanceid' parameter")
            else:
                if private_ip:
                    module.fail_json(
                        msg='private_ip only available with on-demand (non-spot) instances')
                if boto_supports_param_in_spot_request(ec2, 'placement_group'):
                    params['placement_group'] = placement_group
                elif placement_group:
                    module.fail_json(
                        msg="placement_group parameter requires Boto version 2.3.0 or higher.")
                
                
                if instance_initiated_shutdown_behavior and instance_initiated_shutdown_behavior != 'terminate':
                    module.fail_json(
                        msg="instance_initiated_shutdown_behavior=stop is not supported for spot instances.")
                if spot_launch_group and isinstance(spot_launch_group, string_types):
                    params['launch_group'] = spot_launch_group
                params.update(dict(
                    count=count_remaining,
                    type=spot_type,
                ))
                
                
                
                utc_valid_until = (
                    datetime.datetime.utcnow()
                    + datetime.timedelta(seconds=spot_wait_timeout))