While there is some overlap in skills and development between second and third graders, third graders generally demonstrate more advanced academic abilities, social skills, emotional maturity, and independence compared to their younger counterparts in second grade. These differences reflect the natural progression of learning and development through elementary school years in the United States. 

Reading: Third graders typically read more fluently and comprehend more complex texts compared to second graders. They can understand and analyze texts with greater depth and discuss more sophisticated themes and ideas.

Writing: Third graders are expected to write longer and more detailed compositions. They begin to organize their writing into paragraphs and develop their ideas with more coherence and clarity.

Mathematics: Third graders advance from basic addition and subtraction to mastering multiplication and division facts. They work with larger numbers, understand fractions, and begin to explore more advanced concepts in geometry and measurement.