How to Compare Two Lists in Python

🚀 Don't Want to Write Code?

If you just need a quick comparison without writing Python, use our free online tool. Paste your lists, click Compare, and get instant results.

⚡ Method 1: Using Sets (Fastest)

Sets are the fastest way to compare large lists in Python. They use hash tables for O(1) lookup time.

# Using sets - fastest for large lists
list1 = ['apple', 'banana', 'cherry', 'date']
list2 = ['banana', 'date', 'elderberry', 'fig']

# Items in list1 but not in list2
unique_to_list1 = set(list1) - set(list2)
# Result: {'apple', 'cherry'}

# Items in list2 but not in list1  
unique_to_list2 = set(list2) - set(list1)
# Result: {'elderberry', 'fig'}

# Items in both lists
common = set(list1) & set(list2)
# Result: {'banana', 'date'}

📋 Method 2: List Comprehensions

If you need to preserve order or handle duplicates, use list comprehensions.

# Using list comprehensions - preserves order
list1 = ['apple', 'banana', 'cherry', 'date']
list2 = ['banana', 'date', 'elderberry', 'fig']

# Items unique to list1
unique_to_list1 = [x for x in list1 if x not in list2]
# Result: ['apple', 'cherry']

# Items unique to list2
unique_to_list2 = [x for x in list2 if x not in list1]
# Result: ['elderberry', 'fig']

🔍 Method 3: difflib for Detailed Diffs

When you need to see exactly what changed and where, use the difflib module.

# Using difflib for detailed comparison
from difflib import unified_diff

list1 = ['apple', 'banana', 'cherry']
list2 = ['apple', 'blueberry', 'cherry']

diff = list(unified_diff(list1, list2, lineterm=''))
for line in diff:
    print(line)

# Output shows exactly what changed:
# --- 
# +++
# @@ -1,3 +1,3 @@
#  apple
# -banana
# +blueberry
#  cherry