star - What is the difference between LMC and SMC?

The LMC has an apparent size of about 645x550 arc mins, the SMC 320x205.

Both contain several hundred million stars each. The LMC is about 14000ly in size, and is about 10 billion solar masses; the SMC is 7000ly in size, and is about 7 billion solar masses.

The visual magnitude of the LMC is +0.28, the SMC is +2.23.

Both feature a number of interesting clusters, nebulae, and supernova remnants. Notably, LMC is home to NGC 2070, the Tarantula Nebula, and Supernova 1987A.
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The LMC is usually considered an irregular galaxy, though it has a prominent bar, somewhat warped, and a spiral arm. The SMC is a dwarf irregular galaxy, or maybe a barred disc.

LMC is the fourth largest galaxy in our local group, and the third closest to us. SMC is the fifth? largest galaxy in the local group, and the fourth closest to us.

{In a previous version of this response I said: A number of websites proclaim that the LMC and SMC are gravitationally bound to the Milky Way. This has been known to be incorrect since 2007 when Hubble observations showed they are travelling too fast to be orbiting the Milky Way. See also.}

A number of websites proclaim that the LMC and SMC ARE gravitationally bound to the Milky Way. This was based on old information. More recent measurements have challenged this assumption, though further analysis has left open the door for the possibility that the LMC and SMC are gravitationally bound to the Milky Way. We can, however, safely say that the LMC and SMC may be gravitationally bound to the MW.