Embed is used when you have found a widget or embeddable content that you would like to add to a Page. A lot of websites offer the option to get embed code for specific items such as YouTube videos, Weather reports and Public transport schedules.
URL is used for iFraming an entire webpage or special embedding URL's that you can get from specific websites. However, they can be a bit hard to set up sometimes. By default you cannot embed any website since this can pose a security threat. This is why most webpages prevent embedding and for some webpages you need to use special embedding URL to get the embedding working. If a website will not embed correctly you will see the below error.
iFrame Widget Options
Embed: Choose between the three options for iFraming content onto the Page.