The phrase "did not differ greatly" is correct and can be used in written English.
It is used to indicate that two things are very similar to one another. For example, "The results of the two experiments did not differ greatly; they both showed the same trends."
In the knowledge section, the results did not differ greatly when different schools, younger and older students or previous working experience and no working experience were compared.
We tested several different models, but the results did not differ greatly.
The salary standing did not differ greatly from the won-lost standing.
The binding association constants of both gels with SjGST/His did not differ greatly under either condition.
Conversion did not differ greatly with urbanization, but fragmentation was greater in areas with high population density and rapid population growth.
Narendra Modi's victory in the elections marks the end of a long era in which the structures of power did not differ greatly from those through which Britain ruled the subcontinent.
The area showing evidence of gap influence extended a maximum of 2 m beyond the edge of the canopy opening, suggesting that the area affected by gap creation did not differ greatly from the area of physical canopy removal.
Despite depuration of commercial mussels, the organoleptic characteristics did not differ greatly between both mussel products.
Data for Pacific Northwest conifers, although including measurements on some of the tallest trees studied, did not differ greatly from patterns found in other tree species.
The R2 and adj-R2 values for the model did not differ greatly, indicating that nonsignificant terms have not been included in the model.
The commissariat did not differ greatly from that of Imperial Russia's Ministry of Finance and its system.
