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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
```

filters["tag:" + key] = value
    if module.params.get('id'):
        filters['client-token'] = module.params['id']
    
    
    existing_instances_array = []
    for res in ec2.get_all_instances(instance_ids, filters=filters):
        for inst in res.instances:
            warn_if_public_ip_assignment_changed(module, inst)
            changed = (check_source_dest_attr(module, inst, ec2) or
                       check_termination_protection(module, inst) or changed)
            
            if inst.vpc_id and group_name:
                grp_details = ec2.get_all_security_groups(filters={'vpc_id': inst.vpc_id})
                if isinstance(group_name, string_types):
                    group_name = [group_name]
                unmatched = set(group_name) - set(to_text(grp.name) for grp in grp_details)
                if unmatched:
                    module.fail_json(msg="The following group names are not valid: %s" % ', '.join(unmatched))
                group_ids = [to_text(grp.id) for grp in grp_details if to_text(grp.name) in group_name]
            elif inst.vpc_id and group_id:
                if isinstance(group_id, string_types):
                    group_id = [group_id]
                grp_details = ec2.get_all_security_groups(group_ids=group_id)
                group_ids = [grp_item.id for grp_item in grp_details]
            if inst.vpc_id and (group_name or group_id):
                if set(sg.id for sg in inst.groups) != set(group_ids):
                    changed = inst.modify_attribute('groupSet', group_ids)
            
            if inst.state != state: