LTE and 4G are types of connections. They do not use Data, they allow your apps and services on the iPhone or iPad to use the Data access.

Does LTE mean you are using data?

Yes. Anytime you access the internet and you are not on WiFi, you will use data from your plan. If you see "LTE" or "4G", that just lets you know your phone is connected to the cellular data network.

Does enable LTE use more data?

The data connection is just faster so you'll be consuming more data since your connection is faster. It will allow you to do so much more, hence using more data. Then LTE isn't using more data, the USER is.. LTE just transfers data faster.