The voice activation recording is a practical function. When the sound is lower enough, the products will pause voice recording. And when the sound is louder enough, it will continue to record voice. The function is able to optimization the storage space. Besides, there are functions of automatic segmentation and recording mark, which is useful to manage the recording files. Also, other additional functions such as MP3, Repeat, files store will provide great convenience. Please choose according to requirement.
For the Video recorder, the function of Motion detection is similar to the voice activation recording. the product will pause taking video when there is no moving picture. But while it detects the moving object, it will continue to take video. Also some product has function of night vision, which can take video at dark night.
Except the above features, you can choose the suitable products after consider the price, size and appearance etc.