what is the difference between data warehouse engine, data warehouse, olap engine, olap database, data storage engine vs data storage?

I need to clarify the keyword "engine" and what functionality stands behind it. I assume engine is a smaller component of a bigger thing - database. Like a 'car engine' is inside a car. So dwh engine can be plugged into bigger datawarehouse? Olap engine can be used as component of actual olap db? I found this data landscape image on Medium.com with 2 different categories: olap db and olap engine. What is the difference since they have overlapping functionality?