超声波用的是声波，雷达用的是电磁波，这才是最大的区别。而且超声波的穿透能力和方向性都比电磁波强的多，这就是超声波探测现在比较流行的原因。
The biggest difference is that ultrasound uses sound waves and radar uses electromagnetic waves. Moreover, the penetration ability and directivity of ultrasonic wave are much stronger than electromagnetic wave, which is the reason why ultrasonic detection is more popular now.
主要应用场合的区别
Main application differences
1.超声波精度不如雷达。
1. The accuracy of ultrasonic wave is inferior to that of radar.
2.雷达相对价位较高。
2. The relative price of radar is high.
3.用雷达的时候要考虑介质的介电常数。
3. The dielectric constant of the medium should be considered when using the radar.
4.超声波不能应用于真空、蒸汽含量过高或液面有泡沫等工况。
4. ultrasound can not be applied to vacuum, high steam content or liquid foam.
5.雷达测量范围要比超声波大很多。
5. The measurement range of radar is much larger than that of ultrasonic.
6.雷达有喇叭式、杆式、缆式，相对超声波能够应用于更复杂的工况。
6. The radar has horn type, pole type and cable type, which can be applied to more complex working conditions than ultrasonic.
超声波特性
Ultrasonic characteristics
由超声波在介质中传播原理可知，若介质压力、温度、密度、湿度等条件一定，则超声波在该介质中传播速度是一个常数。因此，当测出超声波由发射到遇到液面反射被接收所需要的时间，则可换算出超声波通过的路程，即得到了液位的数据。
According to the propagation principle of ultrasonic in the medium, if the medium pressure, temperature, density, humidity and other conditions are certain, the propagation speed of ultrasonic in the medium is a constant. Therefore, when measuring the time required for the ultrasonic wave to be transmitted and received when it meets the reflection of the liquid surface, the distance through which the ultrasonic wave passes can be converted, that is, the data of the liquid level can be obtained.
超声波有盲区，安装时必须计算预留出传感器安装位置与测量液体之间的距离。
There is a blind area in the ultrasonic wave. The distance between the installation position of the reserved sensor and the measuring liquid must be calculated during the installation.