Difference between Jira server REST API and Jira Service Desk REST API

[aas]

Hello. I have Jira Server instance and Jira SD instance. I need to integrate it: when transition occurs in Jira the transition in Jira SD must be completed. I try to use REST APIs but when I try to make POST request like described here https://docs.atlassian.com/jira-servicedesk/REST/4.4.2/?_ga=2.222370008.2133076669.1571026363-188386877.1559530511&_gac=1.45887120.1567402927.EAIaIQobChMI-42tx7ax5AIVEB0YCh3eNQ2eEAAYASAAEgIYz_D_BwE#servicedeskapi/request/{issueIdOrKey}/transition there're no transition in Jira SD, but this https://docs.atlassian.com/software/jira/docs/api/REST/8.4.2/?_ga=2.256515400.2133076669.1571026363-188386877.1559530511&_gac=1.216344994.1567402927.EAIaIQobChMI-42tx7ax5AIVEB0YCh3eNQ2eEAAYASAAEgIYz_D_BwE#api/2/issue-doTransition works.

So Jira SD REST API doesn't work for JIRA SD, instead JIRA Server REST API. Any ideas?

[fran garcia gomera]

what do you get in the response? are you passing any data in the body of any of the API calls?

[aas]

Well,

POST https://host/rest/servicedeskapi/request/{here is issue}/transition

Response is 400 when use jira SD REST API ("sd.customer.transition.error.transition.unavailable") request body and headers are

 {"id" : "11"},
"additionalComment": {
"body": "Do transition"
} 

X-ExperimentalApi: opt-in

Content-Type: application/json

and authorization 

POST https://host/rest/api/2/issue/{here is issue}/transitions 

Response is 204 when use jira server REST API

body and headers are

{"transition" : {"id" : "11"}}

Content-Type: application/json

and authorization