They are essentially the same, just different size. When I bought my Micro SD for my smart phone it came with an adapter to allow the card to fit in a standard SD slot.
I'm thinking about buying the Nokia 3501, and included with the phone is a 1 GB SD card but the CNet review suggests buying a MicroSD card. Is there a difference between the two? Will the regular SD card hold all my text messages so I won't have to constantly delete my inbox/outbox?