Hugill fired the Lilywhites' winner against Sheffield United at Deepdale, that his ninth goal of the season.
North End agreed the signing of Moult from Motherwell during the week, with the move taking effect on January 1.
But Neil insists it would be wrong to assume he is a replacement for Hugill, a player who was subject of an Â£8m bid from Reading in August.
Neil said: "People will probably be thinking that now we have signed Louis that Jordan will be leaving - that is not the case.
"In the last window we couldn't accept a bid, even if we had wanted to, because we didn't have enough cover.
"Jordan Hugill is not leaving the club, we are not interested in selling Jordan at the moment.
"He has performed very well for us and we are bringing Louis in to give competition to that spot but also potentially to allow us to play two up front at times.
"Louis can play in behind as well, he did that for Motherwell on quite a few occasions when he became the deep-lying striker who gets himself in the box later on in the move.
"We are trying to improve our squad in every window, for what we got him at with the amount of goals he scores, you won't get much better value."
Neil is pleased that North End got the deal for Moult wrapped-up well in advance of the transfer window opening.
The 25-year-old has scored 50 goals for Motherwell in two-and-a-half seasons at Fir Park.
Said Neil: "He brings goals with him, he is a clinical finisher - his record is good at any level, he scores all types of goals.
"With Sean Maguire being out we are a bit light at the top end of the pitch.
"If Jordan was to get an injury we would only have Stephy Mavididi left who has been injured himself recently.
"We have been fortunate that Jordan hasn't picked up an injury because that would have cost us.
"It is a position we have had to address in terms of making sure there is more competition in that area.
"Louis works really hard, he is a good lad and he is everything I associate with Preston in terms of being young, hungry, has ability, wants to learn and get better."