Here's why:
* Different pronunciations: While some characters are shared, their pronunciation can be significantly different. For example, the character "妈" (mā) is pronounced "maa" in Mandarin, but "maa1" in Cantonese (the number represents the tone).
* Different vocabulary: There are many words that are different in Mandarin and Cantonese.
* Different grammar: While not drastically different, there are some grammatical differences, such as the way questions are formed.
However, there are some overlaps:
* Shared writing system: Both languages use the same written characters, although there are some minor differences in simplification and traditional forms.
* Shared cultural context: Because they share a cultural background, speakers of both languages may be able to understand some basic concepts and expressions.
In summary:
* Mandarin and Cantonese are different languages, and speakers of one will not generally understand the other.
* However, some basic understanding is possible due to shared writing and cultural context.
It's important to note that there are different levels of fluency in both Mandarin and Cantonese. A native Cantonese speaker with exposure to Mandarin may understand more than a beginner Mandarin speaker with no exposure to Cantonese.