I think you may be getting confused by terminology. Your question is:
"What are the differences and limitations between enchanting and creating magical items"
As worded, there is no difference between "enchanting" and "creating" as far as magical items go.
What I think you may mean is: "What is the difference between casting a spell on an item to make it magical, and a permanent magical item?"
Here it is best just to realise that casting spells follow the rules in the Player's Handbook (or Basic Rules) and are generally temporary in nature.
When you cast a spell like light, even if you cast it on an object, it is only temporary and lasts only as long as the spell description says it lasts. It does not make the object itself magical (at least, not in a permanent magical way) no matter how many times you cast it.
Spells such as Mordekainen's Magic Sanctum are the exception. They have a specific rule in the description that says "if you cast this spell every day for a year it's effects become permanent". Only very few spells say this (Teleport Circle is another) and it only applies to these spells. It is not a general rule.
Having said that, the rules for creating magical items are pretty abstract and, apart from a recommendation for time and gold, pretty much up to the DM (I went into this a bit with your other question here). If your DM decrees that creating a wagon with a permanent Silence effect requires a year of casting the Silence spell (as well as other expenses), then that's what it takes, but there are no hard-and-fast recipes in the rules.
Also worth noting, as NautArch points out in the comments, that the rules for creating magical items are entirely optional (leaving it open for a DM to decide how such objects are treated in his campaign setting).