Both models
i5-4278U and
i7-4500U are based on
Haswell architecture.
"Haswell is known as fourth-generation core too. It uses 22nm Tri-Gate FinFET (non-planar, ""3D"") technology. It includes four arithmetic logic unit (ALU) and three address generation unit (AGU). This generation is able to run Advanced Vector Extensions 2 (AVX2) instruction set among BMI1, BMI2, ABM and FMA3. At this time, Intel used new sockets: LGA 1150 for desktops and BGA1364 for the mobile CPUs."
Using the multithread performance as a reference, the i5-4278U gets a score of
76.2 k points while the i7-4500U gets
66.1 k points.
Summarizing, the
i5-4278U is
1.2 times faster than the
i7-4500U . To get a proper comparison between both models, take a look to the data shown below.