Neuroscience focusing on human development and disease has long been hampered due to ethical reasons, low tissue availability, and low translatability from animal models. To circumvent these obstacles, we have developed two methods for the investigation of human neural cells in culture. Firstly, we present a robust 2-week protocol for the differentiation of human pluripotent stem cells (PSCs) into forebrain neural progenitor cells. Furthermore, we have used this protocol to differentiate PSCs from humans and chimpanzees. We show that human and chimpanzee cells differentiate in a similar manner and that the difference in interspecies protein abundance is higher than transcript-level differences, suggesting that post-transcriptional mechanisms play a role in the difference between human and chimpanzee brain development. Secondly, we have developed an all-in-one vector-based strategy to convert adult human dermal fibroblasts directly from Huntington’s disease (HD) patients and control individuals into induced neurons (iNs). After 4 weeks of conversion, we performed global analyses of RNA and protein levels by RNA-sequencing and mass spectrometry. In line with our previous results, we found that there are marked differences between HD patients and controls at the protein level but not at the transcriptional level. Taken together, our results suggest that post-transcriptional mechanisms play an important role in the brain both during development and in the adult brain.