What are the differences between app created in developer work and open work?

https://open.work.weixin.qq.com/wwopen/developer#/sass/apps/list

https://developer.work.weixin.qq.com/tool#/tab/apps/list

Can both be installed as third party app in Wecom. If so, kindly do help us with details.

Also if i want to perform an integration between CRM and wecom , how to initiate wecom flow from CRM rather than from Wecom application market?