problem control and error control

In essence, Problem Control is the investigation phase, aiming to turn the 'unknown' (Problems) into 'knowns' (Known Errors). Error Control then is the resolution phase, aiming to turn Known Errors into implemented solutions (when justified). That is in a nutshell what it boils down to.

Difference between change mgmt & release management

Let's start with "Release Management" is the process of managing Product Releases, Process Releases, or Services Releases, from inception through to deployment and maintenance, post deployment. This includes the build, deployment, installation, instantiation, execution, teardown, and rollback of releases in each and every environment (e.g. Development, Systems Integration Testing, User Acceptance Testing, Production, etc.) (NOTE: Most companies usually only relate Releases to Products and not to Processes and Services, however, more and more teams are starting to realize that they need to manage Process and Service improvements, incrementally, through versioned iterations, like they do Products.)

"Change Management" is the process of managing individual or groups of "Changes" from inception, through to deployment and maintenance, post deployment. Again, this includes the build, deployment, installation, instantiation, execution, teardown, and rollback of changes in each and every environment (e.g. Development, Systems Integration Testing, User Acceptance Testing, Production, etc.)

"Change Management" is usually a subset of Release Management. Most mature organizations will increment the Release version if there is at least one new Change that is required, after a Release has been frozen.

What is ITSM

IT service management (ITSM or IT services) is a discipline for managing information technology (IT) systems, philosophically centered on the customer's perspective of IT's contribution to the business. ITSM stands in deliberate contrast to technology-centered approaches to IT management and business interaction. The following represents a characteristic statement from the ITSM literature:

Providers of IT services can no longer afford to focus on technology and their internal organization[;] they now have to consider the quality of the services they provide and focus on the relationship with customers.