Whats the difference between 1800 - 2000

1.d4 Nf6
2.c4 e6
3.Nf3 d5
4.Nc3 Be7
5.Bg5 0-0
6.e3 Nbd7
7.Rc1 c6
8.Qc2 Re8
9.Bd3 dxc4
10.Bxc4 Nd5
11.Ne4 f5 {A weak move. Black gets now a cramped position; better was ...h6.}
12.Bxe7 Qxe7
13.Ned2 b5
14.Bxd5 cxd5
15.0-0 a5
16.Nb3 a4
17.Nc5 Nxc5
18.Qxc5 Qxc5
19.Rxc5 b4
20.Rfc1 Ba6
21.Ne5 {With the well-placed knight and his rooks in command of the open file
white has an easily won game.} Reb8
22.f3 b3
23.a3 h6
24.Kf2 Kh7
25.h4 Rf8
26.Kg3 Rfb8
27.Rc7 Bb5
28.R1c5 Ba6
29.R5c6 Re8
30.Kf4 Kg8
31.h5 Bf1
32.g3 Ba6
33.Rf7 Kh7
34.Rcc7 Rg8
35.Nd7 Kh8
36.Nf6 Rgf8
37.Rxg7 Rxf6
38.Ke5 !! {Now white wins a rook or mates black}