Simularities:
John Boy and Laura are both authors.
John and Charles both support their families by working at a lumber mill.
The general store is run by an easy going guy whose wife is the town busy body.
The Ingalls took in James in Cassandra. The Waltons took in Serena and Jeffrey.
Both families originally had 3 daughters.

Differences:
The Ingalls had 3 children. The Waltons had 7.
The Waltons had electricity and indoor plumbing. The Ingalls didn't.
The Waltons live in Virginia. The Ingalls live in Minnesota.

Similarity:
They both bought things on credit at the store
they both had dogs
They both had lots of friends in the surrounding area
Both families had lots of love
Both the Walton and Ingall children walked to school
Both the Walton and Ingall children went to one room schools

Difference:

Grandparents lived with the Waltons, the Ingalls grandparents did not.

The Waltons had cars, the Ingalls had horses and wagon

The Waltons gathered around the radio after supper, the Ingalls listened to Pa play the fiddle.

The Waltons called their father Daddy, the Ingalls said Pa

The Waltons owned their land, the Ingalls did not