I kept seeing these two differences and was unsure what the differences were between Judah and Israel.
“Israelites had a single kingdom during the reigns of Solomon and David. After the death of Solomon, the country was divided into two independent kingdoms. The southern region came to be called Judah which consisted of the tribes of Benjamin and Judah. Jerusalem was their capital. The northern region was called Israel which comprised the remaining ten tribes. They had the capital at Samaria.”
Another interesting site on the subject: https://lifehopeandtruth.com/prophecy/12-tribes-of-israel/israel-and-judah/
A neat map on the subject: https://www.bibleodyssey.org/en/tools/map-gallery/i/map-israel-and-judah