The Evolution Series 4 locks use a 14mm shackle versus the fahgettaboudit U locks using an 18mm one. Both have locking bolts on both sides of the shackle. The Evolution Mini locks use a 13mm shackle and only have single side locking of the shackle. The other leg uses the classic Kryptonite "bent leg" design. I suspect that the dual locking bolts are probably stronger.

IMO a U lock is probably stronger than a chain due to the thicker material but the choice depends on your individual locking situation. Either should discourage most bike thieves other than professionals. As mentioned NOTHING works for pros with power equipment who want YOUR bike.