Hotspots are static onboarding elements that can exhibit near at hand information about any item of your product.
You can think of a hotspot as an asynchronous box presenting its informative content on demand.
Hotspots do not block user interaction thus, they do not sacrifice the sense of discovery.
In order to acclimatize new users with your UI, for example, you can attract attention to specific elements with a series of pulsing hotspots.
They can be definitive, explanatory, or even humorous, and utilized to subtly remove guesswork from any user experience.
On the other hand, guides are dynamic onboarding flows playing interactive parts within user experience. They educate users on-the-go, thereby serving users the resources they need to resolve their own questions.
Compared to the asynchronous hotspots, guides are in motion. In other words, once a guide is started, the user should finish or drop this flow.
With guides, you can create product tours and respectively show your users where the most important features are. In this use case, main purpose can be defined as making users understand lay of the land.
You can also guide people concurrently with the help of successive, action-driven steps, in order for them to achieve a specific goal.
Both with hotspots and guides, you can support end-users at the right time and cushion their eventual frustration considerably.