As far as I understood, it isn't the same thing. You can get the `instanceId` from the `spotInstanceRequestId`:

````java
DescribeSpotInstanceRequestsRequest describeRequest = new DescribeSpotInstanceRequestsRequest();
describeRequest.setSpotInstanceRequestIds(spotInstanceRequestIds);

// get the results for the requests
DescribeSpotInstanceRequestsResult describeResult = client.describeSpotInstanceRequests(describeRequest);
List<SpotInstanceRequest> describeResponses = describeResult.getSpotInstanceRequests();
// each describeResponse has a getInstanceId method this gives the actual ID
````