Starting from Bluetooth 4.0, it contains two Bluetooth chip modules: the traditional/classic Bluetooth 

module (classic Bluetooth, abbreviated as BT) and the Bluetooth Low Energy (abbreviated as BLE).

Classic Bluetooth is developed and improved based on previous Bluetooth versions such as

 1.0/1.2/2.0 + EDR/2.1 + EDR/3.0 + EDR. Bluetooth Low Energy is developed based on Nokia's wibree standard.

1.Classic Bluetooth Modules (BT)

It generally refers to modules below Bluetooth 4.0 and is usually used for large - volume data 

transmission, such as voice, music, and high - volume data transfer.

Classic Bluetooth modules can be further divided into traditional Bluetooth modules and 

high - speed Bluetooth modules.

The traditional Bluetooth module was launched in 2004. The main representative is the module 

that supports the Bluetooth 2.1 protocol, which was widely supported during the period of the smartphone boom.

The high - speed Bluetooth module was launched in 2009. Its data rate increased to about 24Mbps,

eight times that of the traditional Bluetooth module.

Traditional Bluetooth has three power levels: class1, class2, and class3, which support transmission 

distances of 100m, 10m, and 1m respectively.

2. Bluetooth Low Energy Modules (BLE)

It generally refers to modules of Bluetooth 4.0 or higher. Bluetooth Low Energy technology is a 

low - cost, short - range, interoperable, and robust wireless technology that operates in the 

unlicensed 2.4GHz ISM radio - frequency band.

Because BLE technology uses a very fast connection method, it can usually be in 

an "unconnected" state (saving energy). At this time, the two ends of the link only know about 

each other. The link is only turned on when necessary and then turned off in the shortest possible

 time (transmitting a maximum of 20 bytes each time). Bluetooth Low Energy has no power levels. 

Generally, the transmission power is 7dBm. In an open area, it should be no problem to reach a distance of 20m.

So, which one should you choose, classic Bluetooth or Bluetooth Low Energy?

Classic Bluetooth：

1.For transmitting sound, such as in Bluetooth headsets and Bluetooth speakers. Bluetooth was 

designed for sound transmission, and it is the best choice for short - range audio transmission. 

Now there are also WIFI - based audio transmission solutions, such as Airplay. However, 

WIFI consumes much more power than Bluetooth, and devices cannot be made portable. Therefore, 

fixed speakers may use WIFI, while mobile devices like headphones and portable speakers all use 

the classic Bluetooth protocol.

2.For transmitting a large amount of data.

For example, in some industrial control scenarios, when using an Android or Linux master control 

with an external Bluetooth remote - control device, the SPP protocol in classic Bluetooth can be

 used as a wireless serial port. It is much faster than BLE transmission. It should be noted that 

iPhones do not support this.

BLE Bluetooth:

It has low power consumption and is suitable for small - volume data transmission. Devices like 

remote controls (mice, keyboards) and sensing devices (heart - rate belts, blood - pressure monitors,

 temperature sensors, shared - bike locks, smart locks, anti - loss devices, indoor - positioning devices) 

are currently the most cost - effective means of communication between mobile phones and smart

 hardware. The straight - line distance is about 58 meters. An AA battery can last for a year, and the

 cost of the transmission module is only 10 yuan, which is much cheaper than WIFI, 4G, etc. Although

 the Bluetooth range is a bit shorter, it can directly connect to mobile phones and is very inexpensive. 

Take indoor positioning as an example. If each store in a mall installs a Bluetooth beacon, it can 

achieve indoor positioning with an accuracy of 10 - meter level for mobile phones. The price of a 

beacon is only tens of yuan.

Dual - mode Bluetooth:Such as smart TV remote controls and noise - canceling headphones. 

Many smart TV remote controls with voice recognition need to use classic Bluetooth to transmit sound.

 However, for complex key operations, such as functions not on the original keyboard, the HID key protocol 

of classic Bluetooth is not sufficient, and a private protocol based on BLE is required. Many noise - canceling 

headphones also use a private communication protocol implemented by BLE to adjust the 

noise - canceling effect through an APP.