Harappa shares its name with the civilization it was part of. Both cities were part of the Harappan civilization.
Harappa was around much earlier and much longer. Evidence points to it being founded around 3300 BCE and being in existence for about 2000 years. Archaeologists name five periods of Harappa:
Ravi Aspect of the Hakra phase, 3300–2800 BCE; Kot Dijian or Early Harappan phase, 2800–2600 BCE; Harappan Phase, 2600–1900 BCE; Transitional Phase 1900–1800 BCE; and finally, Late Harappan Phase, 1800–1300 BCE.
By contrast, Mojenjo Daro was built around 2600 BCE and was already abandoned around 1900 BCE, lasting about 700 years. Archaeologists uncovered remains of it in 1919.
Harappa still has a modern day village less than a mile from the archaeological site. It was a railway center under British colonial rule. Archaeologists began uncovering the ruins earlier, in 1826.
There are more similarities than differences between the two cities. However, I list two differences between Harappa and Mohenjodaro below:
1) Geographic Location.
The ancient city of Mohenjodaro (Mound Of The Dead) is situated on mounds located in the modern-day Larkana district of Sindh province in Pakistan. Harappa is located southwest of Sahiwal (150 miles away from Lahore and 250 miles from Karachi). Both are the two greatest cities of the Indus Valley civilization or Harappan civilization.
2) Sculptures and artifacts.
Mohenjodaro is well known for its bronze dancing girl figurines and the statue of the priest-king. Harappa is known for its red and gray sandstone torso figurines. There appear to be no parallels or similarities between the figurines found in both cities. The Great Bath of Mohenjodaro is the largest known public water tank in the ancient world; it may have been used for ritual bathing purposes during its day.
Here are public bathing platforms in Harappa similar in kind to the ones used for washing clothes in some traditional cities in Pakistan and India today.
Both cities were more alike than different in layout and construction. The same type of bricks were used in constructing both Mohenjodaro and Harappa. The earliest artifacts found in both cities were stone seals with elegant animal artwork and Indus script carved into them. A few Indus valley stone seals were also found to have included swastikas, religious symbols prevalent in Hinduism, Buddhism, and Jainism. Phallic symbols and stone seal incarnations of the Hindu god Shiva were also discovered.