Transactions in application-specific Blockchain networks like Bitcoin are quite uniform in terms of size/complexity/cost. That makes the comparison with a conventional system like Visa straightforward.
In smart contract capable blockchain networks like Ethereum or ARTIS, the size/complexity/cost of transactions can vary greatly, up to more than 2 orders of magnitude. For this comparison, we thus use "normalized" transactions.
The Ethereum protocol specifies a fee of 21,000 "gas" for simple transfers of native tokens (e.g. ETH in Ethereum, ATS in ARTIS). This results in the following numbers for max. transaction capacities: