https://en.wikipedia.org/wiki/List_of_Yamaha_productsTyros series
Tyros (1 May 2002)
Tyros 2 (21 June 2005)
Tyros 3 (17 April 2008) Tyros 4 (16 June 2010)
Tyros 5 (13 July 2013)
Genos (31 August 2017)
PSR arranger workstations
See also: § PortaTone PSR series
PSR-1500 (21 January 2004)
PSR-3000 (21 January 2004)
PSR-7000 (1995, export model)
PSR-8000 (8 September 1997, export model)
PSR-9000 (9 Septem000ber 1999, export model)
PSR-9000 Pro (2000, export model)There is almost a difference of a decate between the two models.
Big difference in technology and sound.
The psr 9000 pro as far I can tell from videos on youtube is a keyboard that is made for professional keybordists who played mostly ethnic-oriental music.
That is why it doesn't have on board speakers.
Tyros 3 is still used very much and has similar sound and functions to the latest keyboards.
But if you have the psr 9000 pro for free,try it out first and if you do like keyboards buy a better and newer keyboard like Tyros 3 or something from the psr s series.