Although the words "clear" and "obvious" are often used interchangeably, there are subtle but important differences between them. "Clear" means easy to understand or see; there's no confusion or ambiguity. "Obvious" implies that something is so evident it shouldn't be missed; it's readily apparent. The key difference lies in the degree of perceptibility and the level of mental effort required for understanding. Something can be clear without being obvious, and something can be obvious without being clear.

Let's look at some examples:

• Clear: "The instructions were clear; I understood them perfectly." (Meaning: The instructions were easy to follow and comprehend.) Translation: The meaning of the instructions was easy to understand.
• Obvious: "It was obvious that he was lying; his body language gave him away." (Meaning: His lie was easily apparent, requiring minimal effort to detect.) Translation: It was very easy to understand that he was lying, because of his body language.
• Clear but not obvious: "The solution to the math problem was clear once I saw the formula." (Meaning: The solution became understandable after some effort, not immediately apparent.) Translation: Once I saw the formula, I found the answer to the math problem was easy to understand.
• Obvious but not necessarily clear: "It's obvious he's angry, but I don't understand why." (Meaning: His anger is apparent, but the reason behind it is not understood.) Translation: It's easy to see he is angry, but I don't understand why.

In short, something "clear" requires understanding, while something "obvious" requires recognition. Consider the level of effort required to perceive the information when deciding which word to use. These nuances will make your English sound more sophisticated. Happy learning!