Assembly is ESF and RCHK's way of using a single sign-in method for many of the ESF wide managed apps and portals. Technically speaking, it uses your Microsoft account to sign-in instead of Google. Assembly is for ESF/RCHK teachers only (students do not have access to Assembly). You can find it by clicking on the RCHK launcher.
Gateway is the VLE (Virtual Learning Environment) for all of ESF. It's the information platform for teachers, students and parents. It's here that you that you can find a great deal of important information for the entire community.
Being able to generate a class list or get important details about your class community is easily done with Gateway.