- Is the volume information the total volume of transactions conducted in the last 24 hours?
Yes.
- Why is their value so much different than coinmarketcap and coingecko?
The total 24 hour volume displayed on each of those websites is the sum of the 24 hour volumes in the bitcoin markets they are tracking.
Coinmarketcap and Coingecko track more bitcoin markets and the total 24 hour volumes reported by them are bigger than livecoinwatch.