To add to Jonas' answer, you simply get more when you buy the license from Nexus: the ecoinvent license and access to the ecoinvent original files (the red box below) plus the versions for openLCA (the lila box below).
For the same price:
ecoinvent unfortunately does not reimburse users who bought from them and discover this later. And we of course have effort for providing ecoinvent and it is we think therefore fair if we charge for those where we provide the license; for those who buy from us, we get a reseller fee from ecoinvent. And as you see from Nexus, we sell for the same price as ecoinvent. Of course, some may be "forced" to use other tools, but we of course cannot work for free. And have already about 100,000 users. Thank you for your understanding!