In which cases do we use dictionaries, and in which - lists?

Lists are used when the order of elements matters and/or you need to store a collection of similar data with access by index. Lists are mutable.

Dictionaries are used when data is represented as key-value pairs and quick access to a value by its key is required. Keys must be immutable. Dictionaries are also mutable.

Comparison:

Characteristic	List	Dictionary
Purpose	Ordered collection of elements	Collection of "key-value" pairs
Access	By index (integer)	By key
Order	Preserved (since Python 3.7)	Preserved (since Python 3.7)
Mutability	Mutable	Mutable
Use cases	Sequences, stacks, queues	Mappings, caches

Examples:

List:

# List of names
names = ["Alice", "Bob", "Charlie"]
# Access by index
print(names[0])

Dictionary:

# Dictionary with user data
user_data = {"name": "Alice", "age": 30, "city": "New York"}
# Access by key
print(user_data["name"])