Is this Xanthelasma or Milia or something else entirely? (photos)

More than likely, you have milia.  Milia are small collections of sebum, little pearls of sebaceous material produced when sebaceous glands lose their opening to the outside world, and just keep making the sebum which keeps getting packed harder and harder.These little lumps are not dangerous in any way.  They are not painful, and the only downside to them is that they are unattractive.  If you were my patient, I would take an 18 gauge needle and gently nick the top of the miniature cyst, apply lateral pressure, and normally the pearl of sebum pops out......end of story.  These little cysts are of minor consequence, and they don't require true surgical intervention.With reference to your question about Xanthelasmas, they tend to cluster around the inner canthus of the eye (area between the inner angle of the eye and the nose.  They tend not to be as discreet as milia.  They usually are not isolated but are in clusters, and they tend to be flatter and more yellow than what your photograph indicates.  These also are painless, fatty deposits even less attractive than milia, and these actually need to be surgically removed.

They don't appear to be either xanthelasma or milia.  However they both look benign.  If they bother you or they are growing see an oculoplastic surgeon to have them removed.  The one on the lower eyelid looks like a sebaceous cyst.  Upper eyelid lesion may be a papilloma.     

They look like benign sebaceous cysts but it is best to see an oculoplastic specialist and consider removal, biopsy.

Your small, white eyelid bumps may be milia. If this is the case, these bumps may be unroofed and improved. Consider visiting a reputable dermatologist or facial plastic surgeon to see what might be best for you.Hope this helps.

Sometimes the only way to know is by shaving the bump off and having the pathologist study it under a microscope.  I recommend seeing a fellowship trained oculoplastic surgeon to assess you and discuss if a biopsy is warranted give the risks, benefits, and alternatives.  The American Society for Ophthalmic Plastic and Reconstructive Surgery maintains a regional directory on their website that can hep you find a highly qualified surgeon in your area.