HPC tasks are characterized as needing large amounts of computing power for short periods of time, whereas HTC tasks also require large amounts of computing, but for much longer times (months and years, rather than hours and days).
As an alternative definition, the European Grid Infrastructure defines HTC as "a computing paradigm that focuses on the efficient execution of a large number of loosely-coupled tasks",[3] while HPC systems tend to focus on tightly coupled parallel jobs, and as such they must execute within a particular site with low-latency interconnects.
Conversely, HTC systems are independent, sequential jobs that can be individually scheduled on many different computing resources across multiple administrative boundaries.
MTC is reminiscent of HTC, but it differs in the emphasis of using many computing resources over short periods of time to accomplish many computational tasks (i.e. including both dependent and independent tasks), where the primary metrics are measured in seconds (e.g. FLOPS, tasks/s, MB/s I/O rates), as opposed to operations (e.g. jobs) per month.
MTC denotes high-performance computations comprising multiple distinct activities, coupled via file system operations.