What is the difference between runing playbook on ansible host and from Jenkins

SUMMARY

Failed to connect to the host via ssh: Host key verification failed

I have set of EC2 instance, i want to do application automation through jenkins UI using ansible plugin.

ISSUE TYPE- Bug Report

I am able to run the playbooks from the ansible host, but not from the jenkins UI using ansible plugin.

COMPONENT NAME

jenkins ansible plugin, ec2 instance with pem file

ANSIBLE VERSION
ansible 2.7.9

CONFIGURATION

OS / ENVIRONMENT

Ubuntu 18.04

STEPS TO REPRODUCE
ansible  -m shell -a "free -m" --private-key=/etc/ansible/pem/WSStaging.pem -u ubuntu staging-app
EXPECTED RESULTS

Both ansible host terminal and jenkins Ui need to work the same

ACTUAL RESULTS

I am able to ping or execute any command in ansible server
image

But when I run the same command from the Jenkins using Ansible plugin i am unable to execute it successfully.
Always the same error
Failed to connect to the host via ssh: Host key verification failed.

image

Thanks in advance.