They are different,related, and both equally important.

Cash management is the fundamental of daily job. Running out of cash means financing. Financing means costs. Costs affect an intermediate P&L line. The intermediate line affects the bottom negatively. To compensate some others active lines should be varied ONLY because you run out of cash.
Running out of cash places an "unreal" (let me say this way) burden on sales and/or production.
On the other side, the P&L tells you the general health status of your business. Splitting the P&L over time tells you how you are doing and how you'll likely be doing. Splitting the P&L over clients will tell you which are the profitable ones. Splitting the P&L over products will tell you which are the products which will bring you the most.
It is not difficoult to keep track of both payments and P&L in an Excel file, and use pivots and macros to analyze them.

Probably I'll write something about in my blog in the near future.