Wealth and intelligence are both kinds of power. The most important distinction may be that we think of wealth as outside the agent, whereas intelligence is internal to the agent. So if you change the agent's environment while leaving the agent intact, its intelligence will remain constant, but its wealth will fluctuate.

If it's hard to exactly define where an agent's boundaries are, the distinction might become merely conventional. For instance, if my normal level of intelligence is reliant on ingesting a certain food or nootropic (or meme), then that resource may be viewed as part of my intelligence (like my brain's architecture), or it may be viewed as an environmental factor that modulates how effective my intelligence is at shaping the particular environment it's in.