SOCKS5 or HTTP proxies
The protocol is usually picked at random. The difference shows up in two places, and both are worth knowing about.
How they differ
SOCKS5 works at the connection level and carries any traffic, including traffic that is not a web request at all.
HTTP understands the web only and can read headers. That is the source of both the capability gap and the behavioural one.
Where it shows
First: support on the software side. Some collectors speak only one protocol, and the choice is made for you.
Second: anything that is not a web request. Mail clients, database connections and custom protocols go through SOCKS5 only.
What matters more than the protocol
For most collection work either will do. Speed and failure rates follow from your pacing and your subnet spread.
If your collector speaks both, take whichever is easier to configure and verify.
Checking the setup
Send a request to an address-reporting service through each protocol and compare. If both report the intermediary address, the configuration is correct.
curl -x socks5://user:pass@host:1080 https://ifconfig.me curl -x http://user:pass@host:8000 https://ifconfig.me