ArcGIS API for JavaScript vs. OpenLayers
Take a look at this side-by-side comparison of ArcGIS API for JavaScript and OpenLayers.
At a Glance
ArcGIS API for JavaScript
About ArcGIS API for JavaScript
ArcGIS API for JavaScript is a tool used to embed maps and tasks in web applications.
OpenLayers
About OpenLayers
OpenLayers is an open-source JavaScript library for displaying map data in web browser.