You are not going to find 3550 switches in the lab exam. These have not the same qos capabilities and configuration than 3560. Of course there is some rack rentals where you could have 3550, but under this you will not be able to practice the switching qos section. This is the main difference, qos, others could be other routing capabilities if used as routers in the lab. Both are L2/L3 switches. L2 would be the same, L3 not, and of course hw qos queues and configurations.
If you look at ProctorLabs.com, my favorite rental outfit, they use two 3550s and two 3560s. This helps keep the overall rental cost down and you can still practice evrything that is 3560 specific on those devices.
I agree with Anthony, we at "Micronics Networking and Training Inc" do the same.
CCSI#30832, CCIE# 12410 (R&S, SP, Security)
Sr. Technical Instructor
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