In terms of application, DCS mostly refers to a controlling system, whereas SCADA is a data acquisition and monitoring system. However, it is a really general overview, I can say.
Following you can find some of their differences but bear in mind that their differences may not be limited to these. We will try to make a video about their differences in a more detailed approach.
1. DCS aims to control the processes which are confined in a limited area such as a factory, while the SCADA is used for vast geographical and remote systems such as 'gas transmission stations', 'water management systems' and so on.
As a result, the DCS control system's network could be a local LAN network while the SCADA communication network is somehow different. For instance, it can use a mobile network protocol. However, SCADA can be used for small industries as well, chemical industries to name one of them.
2. As I mentioned above, SCADA also can be used to control a process in addition to data acquisition and monitoring a process. However, these control loops are opened-loop in contrast with DCS systems.