^Saul gives a good explanation. You can also think of the expressions in these terms

like is a comparison

just like is equal to. Saying just like means they are the same, or extremeley similar

Examples:

The food at this restaraunt is like the food in Hong Kong.

The food at this restaraunt is a little bit like the food in Hong Kong.

The food at this restaraunt is a lot like the food in Hong Kong.

The food at this restaraunt is just like the food in Hong Kong. (so: food at this restaraunt = food in Hong Kong)

"Like" and "just like" mean the same thing, when you are comparing two things. The only difference is that when you use "just like", it is to emphasize. For example:

--> The little girl is like her father (comparing the little girl to her father)

--> The little girl is just like her father (emphasizing the comparison between the little girl and her father)

thanks!