There's not much of a difference. 就 as in 就像 functions more like the adverb ‘just’ as in just like, it makes your statement sound slightly stronger than '好像'. Moreover, ‘’就像‘’ is just the abbreviation of '就好像'.

In different context they have usage method 就像have a more affirmative answer Such as:the moon looks like a boat. 月亮好像小船。（metaphor） 月亮就像小船。（metaphor ）in this sentence,就像have a more affirmative answer, more positive tone.

if you want to say 100% alike, we have another phrase for it----一模一样。In chinese understanding, 像can be 99.99%，but it‘s never hundred percents alike。because when it’s 100%，it's no longer alike，it's identical instead。sorry for poor writing as im typing on my phone。

schneiderhu, I think 好像 is more like = очень похож = ex: He is "so alike" (In light of Felix explanation of 好). But then 很像 should be 100% like 好像? Right? As for 就像 is more like = совсем как = "just like". The core meaning of 就 IMHO is "then" and it's secondary modern meaning "just" (as "short time period" and "simple) do (from the point of linguistical evolution for all such "then" terms in other languages) have one point of convergence.

就像=а=похож на....，но 好像= кажется или кажелось