Mices and rats: differences between shǔ, lǎo shǔ, Xiǎo lǎo shǔ, etc What is the difference between all the different available kinds of rat and mices, like shǔ, lǎo shǔ, Xiǎo lǎo shǔ?

Can 鼠 be used alone?

Is 小家鼠 the proper word to mean a nice little mouse in a colloquial sentence (e.g. not in a scientific essay)?

Thanks!
In most conditions, Chinese Mandarin doesn't divide "rat" and "mouse", but 鼠 and 老鼠 can mean different creatures. 鼠 means various of mouse-like creatures, like voles, hamsters, guinea pigs and so on, while 老鼠 only means rat, that grey little creature. 

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