Both go hand in hand simultaneously with cwm being prior.Also while on the topic of roms want to elaborate this possible without cwm as truth in roms are nothing but removed bloatware,alternative apps not native to stock,new fonts,new boot animations,new theme,new kernal,and etc. complied together simultanoeusly.Even on a locked bootloader one can make their own rom given they actually know what their doing its how I'm getting over 5 hours of battery even with heavy use