Find Easter first, then plan everything else around it
Easter moves between late March and late April, and where it falls determines whether this is a good month or a bad one. Look it up before you look at anything else, because it is the only variable in April that is both knowable a year ahead and worth more than every tactic combined.
The rule that follows is simple: book outside the fortnight that brackets it. The week before is nearly as busy as the week after, because European and Latin American school breaks do not align with the US one, and Orlando gets both.
If the Easter week is the only week you have, treat it as a peak trip. That means booking the hotel early, buying Express Pass, arriving before opening every day, and planning fewer parks than you would in a quiet month rather than more.
The last ten days are the best-value window of the spring
Once every district is back at school, late April at Universal Orlando delivers moderate crowds, extended operating hours, warm dry weather and prices below the March average. That combination does not recur until the second half of September, and September carries hurricane risk that April does not.
The weather argument is the strongest part of it. April is Orlando's driest month, which means the afternoon thunderstorm that shapes every summer day has not started, and a full day outdoors is comfortable in a way it will not be again until November.
The one thing missing is seasonal content. Mardi Gras is finishing, the summer programme has not started, and there is no substantial overlay at either resort. If atmosphere is what you are buying rather than rides, this is not your month.
Hollywood loses its March advantage this month
The reason Universal Studios Hollywood stays calm in March is that Southern California schools do not break in March. In April they do, and they break together around Easter, so the park's Easter week runs at a level it does not reach again until the middle of summer.
That flips the coast recommendation for one fortnight. In March, California is the calmer choice; during Easter week, both coasts are bad and Orlando at least has three parks to distribute the crowd across. A compact single park under peak local demand is a specific kind of unpleasant.
Outside that week, April is close to Universal Studios Hollywood's best month on the weather alone. Mid-70s afternoons on a park built across two levels and a long escalator run is worth more here than at any flat park.
Mardi Gras ends this month, and the exact night is not published far ahead
Universal Orlando's Mardi Gras has finished in late March in most cycles and has run into April in some recent ones, so whether an April trip catches it at all is genuinely uncertain rather than a matter of picking the right week. The closing date is published per cycle and has moved between years.
If the concerts are the reason for the trip, treat April as unreliable and book February or March instead. If they are a bonus, check the operator's own calendar a month out and adjust which nights you spend at Universal Studios Florida.
The parade and street party are included with regular admission, so catching them costs nothing beyond being in the right park on the right evening. That makes them worth building an evening around and not worth building a trip around this late in the season.