should i get a macbook or an imac?

I'd recommend considering the following (just some core questions to ask yourself):

• Do you travel a lot, or will the computer mainly be home/desk bound?
• Are there any particular applications you'd like to run?
• Do you have a particular budget you'd like to stick to? Apple MacBooks can get very expensive as soon as you start upgrading the internals, for example.

Once you've had a think about the above, check out the comparison link @BobTheFisherman has included in his reply.

Only you know your specific needs. You can compare the models here:

https://www.apple.com/mac/compare/?afid=p238%7Cs7Tbv57Pz-dc_mtid_1870765e38482_pcrid_567634253012_pgrid_13945976407_&cid=aos-us-kwgo---slid-CqeXKlxt--product-