How are MRP and ERP similar? How do they differ? 

Both MRP and then ERP are tools or more like methodologies that are put in place to sort of make the organization and its overall manufacturing process to be that much more consistent, uniform but also efficient in resource usage.  ERP is used to describe enterprise resource planning and it is considered to be more like an IT based environment where the key goal is to look at what sort of activities are taking place in the different departments of the firm and also how to have the right level of data sharing, coordination and collaboration within them.  This also then relates to MRP which stands for manufacturing resource planning.  Just like the ERP, MRP also seems to be geared at looking at what inventory is being used, how much of that inventory is being used and hen also assigning the different costs in making the different batches of the product. So these are two concepts that work side by side with each other in the arena of product manufacturing.