Please explain how to tell what breast cancer lumps feel like and which lumps are nothing to worry about?

That is a good: ..But hard question. A lump is a lump, be it benign or malignant. Even a physician may be unable to tell the difference by just palpating. If a lump grows over time, i'd be more concerned that if it doesn't but even that can mislead you. Please, do not self diagnose. Make sure you get your mammograms on time and see your doctor about any and all breast issues that may concern you. Best to you.