Dead Metaphor: These are metaphors that have been used so often in the language that they've lost their metaphorical sense and are taken literally. Examples include "grasping a concept" or "fishing for compliments." They are usually the easiest to understand because they have become part of everyday language.

Standard Metaphor: This is a direct comparison between two unlike things. It’s straightforward in its comparison, e.g., "The world is a stage." It's relatively easy to identify and understand because of its direct nature.

Implied Metaphor: This doesn't directly state that one thing is another; instead, it implies the comparison, which requires a bit more thinking to interpret. For example, saying someone "barked" an order doesn't directly compare them to a dog, but it implies it. This can be slightly more challenging to decipher than a standard metaphor.

Visual Metaphor: Often used in visual arts or advertising, this metaphor represents abstract concepts or ideas through visual means. The difficulty here can vary widely based on the visuals and the concept, but understanding them might require some interpretation skills, cultural knowledge, and context.

Extended Metaphor: This is a metaphor that extends over multiple sentences, paragraphs, or even an entire work. It delves deeply into its comparison, drawing multiple parallels between the two entities it compares. Because of its length and complexity, it is generally the most challenging to fully grasp and analyze.