Block
- Occupies entire horizontal ‘row’
- ‘Listens’ to margin padding, and text-align rules
- Does not allow for side-by-side content in browser
- Examples include: h1, h2, h3, ul, ol, li, div, p
Inline
- Only as wide as its content
- does not ‘listen’ to margin, padding, or text-align
- Allows content to show side-by-side
- Examples include: a, span
More on the CSS ‘display’ property can be found here: https://css-tricks.com/almanac/properties/d/display/