What is the difference between a cost element and a cost driver?

Develop a Parametric Model demonstrating the key cost drivers for compressors using following instructions.

What are potential explanatory variables $($from given data$)$ for cost fluctuations?

Do regression analysis $($linear regression$)$ and explain what are cost drivers. For this regression, ignore geography and scroll$/$reciprocating as variables.

From regression results, would you recommend consolidation of volumes as best strategy? Provide your reasoning.

Assume Whirlpool has decided not to consolidate volumes. However, after discussing this with the engineering team and suppliers, they came up with two options to bring down the costs: $($a$)$ reduce energy efficiency rating $($EER$)$ by $0\mathrm{.}25,$ OR $($b$)$ reduce weight by $1$ lb$.$ Based on the cost modeling, what would you recommend if they could only choose one of the options? Please provide your analysis and assumptions $($if any$).$