I have been study about Veneziano amplitude and Virasoro Shapiro amplitude. I want to summarize this two amplitude in the following way, please check that i am understand them properly.
Veneziano amplitude : they are open string amplitude for disk. Usually we called four-open string tachyon on disk as Veneziano amplitude
Virasoro-Shapiro amplitude : they are closed string amplitude for sphere. Usually we called four-closed string tachyons on shpere as Virasoro-Shapiro amplitude.
The similarity between Veneziano and Viraosoro-Shaprio amplitude are they both have Regge and hard scattering limit.
Is there are more difference and similarity for Veneziano and Virasoro-Shaprio amplitude?