Is the law different for children when physical assault takes place?

[AlmostUnbelievable]

By that I mean, if an adult hits and marks another adult, that adult has to report it within 6 months or it won't go any further.

But if an adult hits and marks a child, does the same 6 month rule apply, or is it different for minors?

I wondered if anyone knows.

The 6 month time limit is for summary only offences, I’ve not heard of an exception for if the victim is a minor. Common assault is summary only, but assaults that leave a bruise could be classed as ABH and so not subject to the 6 month rule. There may also be other laws that apply if the victim is a child.

What does it count as if it's something there an obvious injury but not actually a bruise, maybe like a red imprint of a mark that leaves a raised, swollen area?

That would normally be common assault.

What actually happened and why wasn’t a complaint made at the time?

That is definitely a common assault level injury (covers reddening, bruising, swelling, minor abrasions) thus the Limit Of Prosecution (LOP) is 6 months from date of incident. If the individual is not charged or summoned in that time period then it cannot be prosecuted. The only exception is if it’s a racially or religiously offence which has no LOP

And that's the same for children as it is for adults?