光ひかり記き憶おく装そう置ち

• 光ひかりディスク

  光ディスク refers to the optical disc medium itself (e.g., CD, DVD), while 光記憶装置 refers to the device that reads/writes such discs.

• 磁じ気き記き憶おく装そう置ち

  磁気記憶装置 is a magnetic storage device (e.g., HDD), contrasting with optical technology.

Compound of 光 (ひかり, 'light') + 記憶 (きおく, 'storage/memory') + 装置 (そうち, 'device'). A straightforward technical term.