SAP ERP (enterprise resource planing) is a popular software provided to automate and improve various business operations. It was designed by a German-based company known as SAP SE. and basically incorporates various key business functions of any organization from small to large enterprises.
SAP ERP is a broad package process area that consists of several business aspects including product planning, manufacturing, marketing, sales, inventory management, shipping, payment, supplies and finance. In a broader model, ERP includes procurement and production, distribution, accounting, human resource and governance, corporate performance and evaluation, customer service, business intelligence, ecommerce and enterprise asset management among others.
SAP ABAP on the other hand is a language in which the codes in SAP programs are written. If you opt to work in SAP environment as a technical consultant, then SAP ABAP is the programming language you will need to learn. The acronym stands for advanced-business-application-programming, formerly allgemeiner-berichts-aufbereitungs-prozessor, which is basically a German phrase for general processor for report creation.
Essentially, SAP ERP is a business application while SAP ABAP is a programming language. ERP comes in different packages for each business level including SAP business one, all in one and business suite. There are other business applications like SAP CRM, SRM, PLM and PLM. ABAP programming language is used to run and/or communicate with these applications or make any necessary changes to the codes.