Ah, good question. They're different beasts, so let me break it down.

1. Bitcoin SPV (Simplified Payment Verification) Light Client: This is a type of Bitcoin wallet that doesn't need to download the entire blockchain history. Instead, it only downloads the headers of blocks in the longest chain, which saves a ton of space and makes it possible to run on smaller devices like mobile phones.

2. Lightning Network/Node: The Lightning Network is a second-layer solution built on top of the Bitcoin protocol that allows for fast and cheap transactions by creating payment channels between users. A Lightning node participates in this network - opening channels with other nodes, routing payments across them and so forth.

So basically: SPV clients are about making Bitcoin more accessible by reducing data requirements... while Lightning is all about improving scalability with faster transactions! Different tools for different jobs.