The rapid urbanization leads to the dynamic changes of the urban external landscape and forms different urban growth patterns (UGP), which in turn affects the development level of the urban internal functions as well. However, few studies have quantitatively examined the spatial stratified heterogeneity (SSH) and driving mechanism of the urban development level (UDL) under different UGPs. Based on the multi-source geographic data of 368 Chinese cities, this study identified the UGP at the patch scale from 2010 to 2020. It furthermore quantified the UDL of newly added construction land. In order to reveal the SSH pattern, motivating factors, and interaction mechanism of the UDL under different UGPs, this paper chose to use the optimal parameter-based geographic detector (OPGD) model, which accounts for the modifiable areal unit problem (MAUP). The results indicate that: 1) There are significant spatial differences in the UDL among different UGPs. Namely, the infilling pattern exhibits the highest UDL, followed by the edge pattern, and the outlying pattern, which has the worst UDL; 2) The SSH of the UDL is defined by the interaction of multiple factors. Different UGPs have both differences and similarities in their motivating factors, thus affecting the spatial distribution of UDL. GDP density and road network density are the two factors with the strongest driving force for all UGPs. Specifically, the UDL of infilling-expansion areas is more sensitive to the industrial structure and infrastructure conditions. On the other hand, factors such as residential density and socio-economic activities are more important to the UDL of edge-expansion areas, while population, topography, and location factors have a stronger influence on the UDL of outlying-expansion; 3) A change of spatial scale will result in the heterogeneity of the influence of motivating factors in each UGP. In general, the systematic comparison of the SSH and driving mechanism of UDL under different UGPs helps us explore high-quality and sustainable urbanization paths. As a result, this scientific field is given theoretical basis for urban planners and managers to rationally regulate external urban forms and optimize the internal structure layout.