  Two populations of twisted magnetic field tubes, or flux ropes (hereafter,
FRs), are detected by in situ measurements in the solar wind. While small FRs
are crossed by the observing spacecraft within few hours, with a radius
typically less than 0.1AU, larger FRs, or magnetic clouds (hereafter, MCs),
have durations of about half a day.
  The main aim of this study is to compare the properties of both populations
of FRs observed by the Wind spacecraft at 1 AU.
  To do so, we use standard correlation techniques for the FR parameters, as
well as histograms and more refined statistical methods. Although several
properties seem at first different for small FRs and MCs, we show that they are
actually governed by the same propagation physics. For example, we observe no
in situ signatures of expansion for small FRs, contrary to MCs. We demonstrate
that this result is in fact expected: small FRs expand similarly to MCs, as a
consequence of a total pressure balance with the surrounding medium, but the
expansion signature is well hidden by velocity fluctuations.
  Next, we find that the FR radius, velocity and magnetic field strength are
all positively correlated, with correlation factors than can reach a value
>0.5. This result indicates a remnant trace of the FR ejection process from the
corona. We also find a larger FR radius at the apex than at the legs (up to
three times larger at the apex), for FR observed at 1 AU.
  Finally, assuming that the detected FRs have a large-scale configuration in
the heliosphere, we derived the mean axis shape from the probability
distribution of the axis orientation. We therefore interpret the small FR and
MC properties in a common framework of FRs interacting with the solar wind, and
we disentangle the physics present behind their common and different features.
