Hop additions & perceived bitterness

So if you add larger amounts of hops in longer intervals VS adding smaller amounts in shorter intervals, but the over all IBU's are the same, can you tell a difference? I understand the difference in flavor additions will affect hop flavor/aroma, but what about overall bitterness?

i.e.

1.5oz Tettnanger 3.7aa 90min
1.25 Cascade 5.5aa 60min
0.25 Fuggle 4.2aa 20min
0.5 East Kent 6.1aa 1min
36.9 IBU's

VS

1oz Tettnanger 3.7aa 90min
0.75 Cascade 5.5aa 60min
0.5 Tettnanger 3.7aa 30min
0.5 Cascade 5.5aa 20min
0.5 East Kent 6.1aa 15min
0.25 Fuggles 4.2aa 1min
34.6 IBU's

The overall bitterness should be the same. The amount of isomerized AA's should be about the same if the calculated IBU"s are the same. The flavor and aroma profiles, as you noted, will be a bit different.
However, since the times different varieties and amounts of hops are boiled changes, you may get a slightly different bittering characteristic. Different varieties can add slightly different bittering characters to the beer - generally varying on a 'harsh' to 'soft' continuum. I doubt the changes here would make a very perceptible difference, though.

Hops depend on freshness. The fresher the better...Long term and short term aging will be better if the hops are super fresh.

Hop variety is less important when you factor in the duration of the boil...Longer boil for bitter won't make a darn bit of a difference in terms of overall flavoring affect. A 60-90 minute boil of any hop is going to boil out a lot of it's original character.

We can't tell you how fresh your hops are because we don't know. Use your nose. If the hops didn't smell good why would you add them to the aroma addition? Or if they smelled subtle...maybe just boil them off.

The bottom line is fresh hops rule...pellets drool. Sadly we can't get just go pick what we need during harvest because the big corporate guys have already ordered the goods...

The fresher the better. Don't get me wrong... I likeike hop pellets but I will under no conditions use a a dry pellet for dry hopping. When I can get t he fresh hops I'll use them...otherwise they get dunked in hot water.

I think most home brewers destroy good beer by dry hopping. Unless of course were talking about homgrown sticky good hops...Night and day difference.

there is a technique referred to as hopbursting where you add large amounts of hops towards the end of the boil. It is primarily for giving a real strong aroma but it gives the beer a lot smoother bitterness like what skyforger was saying. At lower ibu levels i doubt it'll have much effect either way. It's mostly noticeable in ipas where the bitterness can be off the charts and either come through smoothly or slap you across the face

You probably won't notice much of a difference in traditional "bittering" additions- the flavor from a 30 minute boil isn't much different than a 90 minute boil (IBUs calculated to be the same, of course).

However, late hops will change the perceived bitterness and flavor. Two ounces of hops added at 15 minutes tastes completely different than .75 ounces added at 60 minutes, even though the IBUs may be the same.