I see different meanings. Like means similar to or in imitation of; such as means for example or in the same category as. Very similar things/persons may be in the same category - thus the seeming interchangeability.
1.person such as X = person, for example X
2.Person like X = person similar to X
3.practices such as these = practices of this type (these are examples)
4.practices like these = practices similar to these