Mental health Step-up, Step-down services (SUSD), also known as subacute services or Prevention and Recovery Services, have emerged to fill an identified gap between hospital-based inpatient care and clinical community-based mental health support. Conclusion. In conclusion, the major differences between step-up and step-down transformers were listed in this article. The most significant difference between them is that, the step-up transformer is used to convert low-end voltages to high end voltage, whereas, the step-down transformer is used to transform the high-end voltage to low-end voltage. A transformer is a device used to step up or step down the electrical voltage. It uses the process of electromagnetic induction to transfer energy from one circuit to another. The transformer consists of three parts. The primary winding, Secondary windings, and magnetic core. EQ6eAM.