It’s a bit odd/unhelpful that this article only compares Matic’s plasma flavor to Loom’s, since Loom is so specialized to a specific use case and at this point there are many plasmas out in the wild with intended use cases that are more similar to Matic’s. It’s difficult to make a direct comparison between OmiseGO and Matic based on the information here because they haven’t shared much detail about their specific plasma flavor, beyond saying that it uses PoS and accommodates both ERC-20 and ERC-721 (vs Loom’s current DPoS with only ERC-721 currently supported, and OmiseGO’s current PoA with only ETH and ERC-20 currently supported). The other comparisons they made (POA, Go Network, Truebit) have very little in common with plasma in terms of the basic problems they’re trying to solve, so not really relevant to this question.
The other major architectural difference that I could discern was that it looks like Matic is using an account/balance model, whereas as far as I know OmiseGO’s is still working with a modified UTXO model for their plasma implementation.
As far as the full tech stack is concerned, they appear to be putting out a wallet that is expected to be the default front end for use on their network, unlike OmiseGO’s white label wallet suite which focuses on a customizable back end.