3mm or 5mm phototransistor?

is there generaly a difference between 3 and 5 mm phototransistor? Such as sensitivity or direction. Or is it only different package of the same device?

Different phototransistors have different properties.

Consult the data sheet for the particular device for the details.

I compared 2 datasheets from the same manufacturer and differences are very discrete at first glance. Only difference I noticed is larger typical collector current at refference irradiance - 2.5 mA for smaller one (!) and 2.0 mA for larger one. If nothing else I would expect the larger one will be more sensitive what is not the case. Considering the 5mm phototransistor is slightly less sensitive, slightly more expensive and larger are there any advantage using it?

EDIT: There are links to “reference” phototransistors
3 mm one
5 mm one

EDIT2: After more careful looking into datasheets and comparing graphs I have found more differences. But it is quite confusing. Datasheet of 5 mm phototransistor states typical collector current at Ee = 1 mW/cm2 and Vce = 5V is Ic = 2 mA. But graph Ic vs Ee @ 5V shows about 2.5 mA at those conditions while graph Ic vs Vce shows 7 mA.
For 3 mm phototransistor the value stated in table is 2.5 mA but Ic vs Ee graph shows 1 mA while Ic vs Vce graph shows 1.5 mA.
I got impression that collector currents grows faster with increasing light intensity in the larger phototransistor but it is hard to tell when each graph shows different numbers. My conclusion would be to use larger phototransistor when light conditions are nearly constant and you need fine resolution. The smaller one is better for detecting larger differences in light. Is it true or it cannot be generalized this way and properties of phototransistors are completely unrelated to their package?

properties of phototransistors are completely unrelated to their package?

The package could have some effect, if otherwise identical components are packaged differently.

The data sheet is your best source of information.

Here, I've added the 5mm plot (red) to the 3mm (blue) for comparison. Looks like the collector current increases at a higher rate in the 5mm phototransistor, but they show a larger range of operation (bandwidth) for the 3mm phototransistor.