嗎 = the speaker is asking a question. You only use "?" after it. 嘛 = expresses the subjective feeling of the speaker. Let's look at an example: 1. 這個糖很好吃嗎？(Is this candy tasty?) 2. 這個糖很好吃嘛。(Hmm, this candy is tasty.)

嘛 1, the reason is obvious: What I said is right.我说的当然是对的嘛. 2,tone words, no real meaning, often placed in front of the sentence, can be connected to any sentence, this usage from Japanese Comics: Well, today the weather is good.嘛，今天天气真好。 3,Used in the sentence to a standstill, to arouse the listener for the following note: science ~, you have to pay attention to seeking truth from facts. 科学嘛，就得讲究实事求是。 吗 The auxiliary, at the end of a sentence, interrogative or rhetorical tone，Do you have breakfast？你吃早饭了吗？ PS：You look like Asian Brazilian, is your family from Japan？

Generally speaking."嘛‘’是语气词。而“吗”是表反问的意思。

嘛是肯定语气，吗是疑问语气。

In some question you need to use the“吗”at the end of sentence “嘛”is a model particle，use at the end of sentence e.g. 你想点一杯咖啡吗?would you like a cup of coffee? 咖啡味道不错嘛。hmm,the coffee taste good