For me, LSP mainly means network connectivity services. If an ISP connects you to the Internet, an LSP connects you to Lightning. You can provide internet services not as an ISP, or Lightning services not as an LSP. The main service an LSP provides is liquidity services via opening channels.

River offers a Lightning API that allows developers to easily integrate with the Lightning Network via a simple HTTP API. We support sending and receiving to and from BOLT11 invoices, LNURLs, and onchain addresses, all without having to worry about channels, liquidity management, peer selection, or infrastructure.

River is a direct Lightning Service provider as opposed to a Liquidity Service provider (eg. Magma, Surge, etc.)

LSP is a Lightning Service Provider. Our current focus lies on providing techniques and the liquidity to create a great wallet/node experience. You can get a channel from our widget for example.

On the other hand, Synonym is developing the Bitkit wallet and focuses on innovative peer2peer tech (Slashtags) to further decentralize the web. We focus heavily on open source software.

Sure! So at @voltage_cloud, we're an infrastructure provider for Bitcoin. That means we provide everything you need to build & use Bitcoin and the Lightning Network. We provide infrastructure (node hosting & management), connectivity (Liquidity Service Providing), analytics (metrics, accounting, insights), and backend services (Esplora, RGS, etc). We help companies incorporate both Bitcoin Layer 1 and Lightning Layer 2 into their products and services. We help folks go from testing and idea to scaling in production very easily.