Qualcomm msm is the abbreviation of Mobile Station Modem, that is, mobile baseband workstation, refers to a mobile processor with a baseband chip, which is actually the baseband built-in mobile phone processor (soc) series.
qsd, short for qualcomm snapdragon, was only given to Qualcomm's first scorpion architecture processors, which were only used by the qsd8250, qsd8650, qsd8250a, qsd850a, and later discontinued. That is, the origin of the current snapdragon name, which is an honorary name used to commemorate Qualcomm's first batch of arm v7 processors.
apq is ap only, that is, the abbreviation of application processor only, that is, can only be an application processor (not a baseband processor) - ap is the opposite of bp (baseband processor, signal baseband processor) - a mobile processor without baseband. A family of mobile phone processors without built-in baseband. Can only be used for wifi tablet, or external baseband use.
In addition, there are:
mdm -- Mobile Data Modem, data card solution, is actually baseband, used for external baseband, wireless network card control, etc.
QSC--Qualcomm Single Chip, single chip, mainly used in wifi, gps master, car chip, and other microprocessing fields.
mpq - media processor only, media processor, is actually a large size version of the apq series, mainly used in smart TV, smart refrigerator and other smart appliances, intelligent engineering vehicles.