List comprehensions and dictionary comprehensions are a powerful substitute to for-loops and also lambda functions. Not only do list and dictionary comprehensions make code more concise and easier to read, they are also faster than traditional for-loops.

In short, list comprehension is a concise way to create lists by combining looping, conditional statements, and value manipulation into a single line of code. Dict comprehension is a similar concept, but it is used to create dictionaries by defining key-value pairs based on an iterable and optional condition. Both comprehensions provide a compact and efficient syntax for creating lists and dictionaries in Python.