I want to control a hydromotor as a hydraulic axis in Simotion. The hydromotor is activated by a proprotional valve (+-10V).
I suppose If I do it on Profibus, my profibus has to be clock synchronous to servotask, I need to use high feature IM151  and high speed or high feature anolog output.

A high speed analog output will certainly work, but a high feature anolog output is can also be operated clocksynchronous (analog output voltage updated with every servo cycle).
So what reasons should there be to use high speed analog output in spite of high feature? Are both updated every servo cycle?

To complete my question : if my servocycle is 2ms, will it make a difference if I use High speed AO in spite of High feature?
For 1 ms I suppose I need High speed?

I remember looking at this when we were thinking of changing one of our servo-motor controlled axis to hydraulic control.  We never did it (thankfully), but here is what I remember.

In any case, you will need the High Feature Interface module to do synchronous communication.

For the output cards, either high speed or high feature will work,  The high feature is a little slower (0.5 vs. 0.25 ms) but has higher resolution (15 bit + sign for HF, 14 bit + sign for HS).

I'd choose the cheaper one, but that's just me.

Edit:  I read the datasheet wrong.  Both cards have 15 bit + sign resolution.  I'm not sure what addition features you get when you get the High Feature version.

Hi.

I can't tell you directly which one is better for you application, as I have no clue about hydraulic.

But for sure HS module offers shorter delay (dead time) and much better dynamic response.

HS:

- Minimum possible time for the isochronous DP cycle (T_DPmin): 250 µs

- Minimum possible conversion time of the output modules: (T_WA): 100 µs

HF:

Minimum time for the synchronous DP cycle (T_DPmin): 0.7 ms-

Minimum conversion time of the output modules: (T_WAmin): 0.5 ms

Sometimes is good to have as reference some experienced condition: that's the reason why I want to mention the last machine working with 20 hydraulic axes with the on board box connections as follows:
6ES7 151-1BA02-0AB0 as ET200S interface
6ES7 135-4LB02-0AB0 as analog output for the proportional valves
6ES7 138-4DB03-0AB0 Fast as SSI interface for the position.
The result is the positioning accuracy 0,001 mm.

Simotion D435-2 (also managing some other electric axes).

pigroplc

Sometimes is good to have as reference some experienced condition: that's the reason why I want to mention the last machine working with 20 hydraulic axes with the on board box connections as follows:
6ES7 151-1BA02-0AB0 as ET200S interface
6ES7 135-4LB02-0AB0 as analog output for the proportional valves
6ES7 138-4DB03-0AB0 Fast as SSI interface for the position.
The result is the positioning accuracy 0,001 mm.

Simotion D435-2 (also managing some other electric axes).

pigroplc

So, back to the OP's question.

If the SERVO cycle is 2ms, then it makes no difference. Get the cheaper one.

If less, go with the HS card. 

The update and settling time of the card needs to be faster than the data coming in.  Get the cheapest one that fulfills that requirement.

I sound like an engineering manager with a budget.