Why do I get different solutions for these two systems of differential equations? Which solver is recommended?

%First Function

function dF=Bisymmfuenf(t,F,mu)

kappa=100; alpha=3.5; k=0.44; phi=1.5; gamma=0.2; s=0.005; c=0.01; dF=zeros(5,1);

gcw=1-s*(F(1)^2+F(2)^2)-c*(F(3)^2+F(4)^2);

gccw=1-s*(F(3)^2+F(4)^2)-c*(F(1)^2+F(2)^2);

dF(1)=kappa*(F(1)-alpha*F(2))*(gcw*F(5)-1)-k*(F(3)*cos(phi)-F(4)*sin(phi));

dF(2)=kappa*(F(2)+alpha*F(1))*(gcw*F(5)-1)-k*(F(4)*cos(phi)+F(3)*sin(phi));

dF(3)=kappa*(F(3)-alpha*F(4))*(gccw*F(5)-1)-k*(F(1)*cos(phi)-F(2)*sin(phi));

dF(4)=kappa*(F(4)+alpha*F(3))*(gccw*F(5)-1)-k*(F(2)*cos(phi)+F(1)*sin(phi));

dF(5)=gamma*(mu-F(5)-gcw*F(5)*(F(1)^2+F(2)^2)-gccw*F(5)*(F(3)^2+F(4)^2));

%Second Funktion

function dF=Bimatfuenf (t,F,mu)

alpha=3.5; kappa=100; s=0.005; c=0.01; gamma=0.2; k=0.44; phi=1.5; dF=zeros(5,1);

dF(1)=kappa*((1-s*(F(1)^2+F(2)^2)-c*(F(3)^2+F(4)^2))*F(5)-1)*(F(1)-alpha*F(2))-k*(cos(phi)*F(3)-sin(phi)*F(4)); dF(2)=kappa*((1-s*(F(1)^2+F(2)^2)-c*(F(3)^2+F(4)^2))*F(5)-1)*(alpha*F(1)+F(2))-k*(cos(phi)*F(4)+sin(phi)*F(3)); dF(3)=kappa*((1-s*(F(3)^2+F(4)^2)-c*(F(1)^2+F(2)^2))*F(5)-1)*(F(3)-alpha*F(4))-k*(cos(phi)*F(1)-sin(phi)*F(2)); dF(4)=kappa*((1-s*(F(3)^2+F(4)^2)-c*(F(1)^2+F(2)^2))*F(5)-1)*(alpha*F(3)+F(4))-k*(cos(phi)*F(2)+sin(phi)*F(1)); dF(5)=gamma*(mu-F(5)-(1-s*(F(1)^2+F(2)^2)-c*(F(3)^2+F(4)^2))*F(5)*(F(1)^2+F(2)^2)-(1-s*(F(3)^2+F(4)^2)-c*(F(1)^2+F(2)^2))*F(5)*(F(3)^2+F(4)^2));

%I call them like this

tspan=0:0.001:1000; E0fuenf=[0.001 0 0.002 0 0]; mu=1; [t,Bisymmfuenf10ode15s]=ode15s(@Bisymmfuenf,tspan,E0fuenf,[],mu); [t,Bimatfuenf10ode15s]=ode15s(@Bimatfuenf,tspan,E0fuenf,[],mu); %or with ode45

[t,Bisymmfuenf10ode45]=ode45(@Bisymmfuenf,tspan,E0fuenf,[],mu); [t,Bimatfuenf10ode45]=ode45(@Bimatfuenf,tspan,E0fuenf,[],mu);

[Torsten]

Before calling the solvers, try

options = odeset('RelTol',1e-8,'AbsTol',1e-8);

Best wishes

Torsten.