Emittors and Collectors in a transistor, what exactly makes them different?
Short answer is their doping level different. 

Firstly, emitter doping is heavily doped relative to collector since good amplification needed. That is also why there is two gain parameters \$\beta_F\$ (forward current gain) and \$\beta_R\$ (reverse current gain). 

The reason why we doped emitter heavily is decreasing the hole component of the base current not increasing electron component of emitter current. 

All purpose is increasing emitter efficiency which defined as:

$$\gamma = \frac{I_{E_n}}{I_{E_n}+I_{E_p}}$$

\$\gamma\$ becomes larger with smaller \$I_{E_p}\$. Increase in \$\gamma\$ increase current transfer ratio and the current gain.

$$\alpha = B \gamma$$
$$\beta = \frac{\alpha}{1-\alpha}$$