What is the difference between them?

These code are right:

a=0.336;
Ta=9.476;
Te=1.208;
Tw=1.498;
eqh=[0.661;0.619;0.568];
ex=[-1.24;-1.346;-1.441];
en=-ex;
ey=[0.376;0.705;0.968];
eqx=[-0.309;-0.357;-0.392];
eh=[1.594;1.583;1.545];
eyqh=[0.642;0.78;0.897];
a0=a*Ta*Te^2;
syms bt Td Ki Kp;
a1=[];a2=[];a3=[];a4=[];exqh=[];

for i=1:3
        Kp=1/bt;
        exqh(i)=en(i)*eqh(i)+eqx(i)*eh(i);
        Ki=1/(bt*Td);
        a1=Ta*Tw*eqh(i)+a*Te^2*en(i)+a*Te^2*ey(i)*Kp
        a1(i)=a1
end

But these code are wrong:

a=0.336;
Ta=9.476;
Te=1.208;
Tw=1.498;
eqh=[0.661;0.619;0.568];
ex=[-1.24;-1.346;-1.441];
en=-ex;
ey=[0.376;0.705;0.968];
eqx=[-0.309;-0.357;-0.392];
eh=[1.594;1.583;1.545];
eyqh=[0.642;0.78;0.897];
a0=a*Ta*Te^2;
syms bt Td Ki Kp;
a1=[];a2=[];a3=[];a4=[];exqh=[];

for i=1:3
        Kp=1/bt;
        exqh(i)=en(i)*eqh(i)+eqx(i)*eh(i);
        Ki=1/(bt*Td);
        a1(i)=Ta*Tw*eqh(i)+a*Te^2*en(i)+a*Te^2*ey(i)*Kp
      
end

The difference between them is

a1=Ta*Tw*eqh(i)+a*Te^2*en(i)+a*Te^2*ey(i)*Kp
        a1(i)=a1

and

        a1(i)=Ta*Tw*eqh(i)+a*Te^2*en(i)+a*Te^2*ey(i)*Kp