Depends on the switch.
Layer 2? Layer 3? Managed? Stackable? Ports? Speeds? Fiber/Copper? PoE?
There are vast fundamental and technical differences between what is called a "Smart" switch (i.e. Layer 2.5) and the Layer 3 switches offered by Cisco, Foundry, ProCurve, and the like. There are also design choices based on your network needs that come into play. What it comes down to is a Layer 3 switch is designed more for a coherent network environment whereby all switches can be linked together and managed as one large framework. This means you have one "core" switch that manages the network settings on all the other "Edge" switches.
The $2-300 switches you see being sold by Dell/NetGear/Linksys/Etc are usually unmanaged Layer 2 switches that support QoS and VLAN for VoIP. These are usually for companies where you can have everyone plug into one switch and you have no real distributed network needs. These will typically not help you diagnose network issues, control loop's in your network (spanning tree), configure one switch as the master to control traffic and the other switches as slaves, etc.
A third noteworthy point is that the Layer 3 switches tend to be built on a more mission-critical enterprise level. Better power-supplies, better PCB designs, better component selection, etc. The cheaper "business" class switches usually have better components then the consumer ones but the design is usually sub-par for most enterprise-class switch gear. What you can do is use an expensive Layer 3 Managed switch as the "Core" switch, and the cheaper switches as "Edge" switches. What you will loose is some managed services and monitoring across the network but it's one method for slimming the budget if push comes to shove.
These aren't all the differences but they're probably the easiest to explain without going to 10-pages of specifics
