LCE isn't a product like Lithium Carbonate ( Li2CO3 )LCE is a...

LCE isn't a product like Lithium Carbonate ( Li2CO3 )
LCE is a term used to equate and "compare" the different lithium products.

https://www.savannahresources.com/lithium/lithium-overview/

Trade and data reporting in the lithium industry

Trade in lithium is largely centred around key lithium raw materials and chemicals such as spodumene concentrate, lithium carbonate and lithium hydroxide which vary significantly in their lithium content. In parallel with this, reference data relating to lithium grades in mineral assays and ore resources and reserves for hard rock and brine projects are also reported using a number of differing measurement units, e.g. ppm Li and percentages of Li, Li₂O, or lithium carbonate. To normalise this data, market participants will often also report data in terms of “lithium carbonate equivalent” or “LCE” so that information can be easily compared on a like-for-like basis. Conversion to LCE is based upon the formulae in the table below.

Conversion factors for differing lithium substances:
Another source, this one includes LiCl which is aptly described as the "crude oil" of lithium.
Many processes try and convert their brine to LiCl before further processing produces one of the typical products - carbonate, hydroxide etc.




In terms of hydroxide vs carbonate... the argument is that there will be so much demand that it doesn't matter.
Also if you refer to above, many projects at some stage in their production has LiCl which can then go either way if the economics support it.

Battery tech determines which matterial is preferred.
Currently we have NCM, NCA, LFP and the many possibilities ( solid state, lithium sulphur etc )
I remember Tesla was/is looking at LFP instead of NCM for some application because of the cost and availability issues of cobalt.