Enclosing vs non-enclosing
Enclosing elements display the content by the browser for the views whereas non-enclosing tags are for the browser to read and not display. Non-enclosing elements provide a reference to what needs to be displayed like an image or link. Additionally, non-enclosing tags need to give more specific information for the web to read to be able to reach the links and images.
Attributes.
Attributes are the additional, specific information given to the browser for non-enclosing tags. Sources need to be given, whether an image is being referenced from the internet with a provided link or from a folder. Attributes also provide on screen text for screen readers for visually impaired for if an image does not load.
Block elements.
Block elements are connected to their parents thus when the parent expands so does the block element child. These elements are the full width of the browser and would create a new line and have no room for another tag of elements to sit next to it. These block-level elements display much larger than the text within them and would need CSS styling to perform as needed.