Definition 1: The positive effect of a process change effort.
Source: American Society for Quality (ASQ), Glossary
There are three types of improvement. Continuous improvement is gradual never-ending change, whereas continual improvement is incremental change. Both types of improvements are what the Japanese call Kaizen. Breakthroughs are improvements but in one giant leap - a step change. However, the method of achievement is the same but breakthroughs tend to arise out of chance discoveries and could take years before being made (see illustration).
Source: Knowledge Hub, Chartered Quality Institute