Based on my industry experience:
1) EPM acronym is most often used to describe IT systems which support activities within financial planning and analysis (FP&A) business function. That includes management accounting, budgeting and KPI setting. Biggest vendors of such systems are Oracle and SAP.
Working within EPM field prepares you for leading FP&A and may help you become CFO someday.
2) Business Transformation often refers to a project office which manages initiatives on improving sales, cost structure, technology or organization depending on the company.
Working within Business Transformation will help you get a more senior job with stakeholders of your projects. For example, a management role in other business functions or an experienced hire role in a consulting firm which supports your employer.