OP, it would have been nice to include the links to the specific devices you were looking at.
I downloaded datasheets for BC549 and BC337,http://datasheetz.com/data/Discrete%20Semiconductor%20Products/Transistors%20(BJT)%20-%20Single/BC549C-datasheetz.htmlhttp://www.fairchildsemi.com/ds/BC/BC337.pdf
The most important parameters to consider are probably BC549, BC337:
Ic max = 100 mA, 800 mA
Vceo max = 30V, 45V
hFE = 100-800, 100-250
For general use, they're fairly comparable transistors, and both should work in most ckts.
The BC337 has a better current capacity.
However, your comment about "works fine without resistors" leads one to wonder, as
you basically never see bipolar transistor ckts without some Rs in there.